NC with kids til engagement is not, IMHO, realistic. How would you feel if you were 8 or 10 or 15 and first met your future stepparent when s/he was engaged to your bio parent? Also, what if when they DO meet, they HATE each other?
IMO, a more realistic approach MAY be no contact (and esp sleepovers) with other men/women until they've been dating x period of time or w/o the other parent's consent, which shall not be unreasonably withheld. IOW, if your new GF has a crystal clear criminal record, no history of drug/alcohol abuse, etc then it's not reasonable for XWW to withhold consent. BUT, if she's had 2+ DUIs (or a recent one), long history of bad checks, fraud, etc., then it's not unreasonable for XWW to put the brakes on things (as we all know, limerance can create a TON of blind spots). Now, whether refusal to consent is "unreasonable" or not, is a matter of opinion... which would put you back in court. I have no idea how a court would view that if the crap hit the fan.
I think most parents (even those who D after infidelity - tho prolly waaaay less likely when the new person is an AP) want to have a cordial & respectful relationship with the X's new GF/BF/SO... cuz it's what's best for the kids to not have bio mom & dad fighting about it (those little buggers can sense tension a mile away). But - as already said - limerance is a bitch and can put some seriously dark blinders on folks, who are apt to take their X's reasonable concerns about a new SO into a bad emotional space (eg my X just doesn't want me to be happy... or my X is just jealous that I have someone in my life and s/he doesn't). So it's really important to try and think and process through some of that, cuz it's not "about" the bio parent... it's "about" the KIDS.
Think of the custody/parenting plan as the FALL BACK position. IOW, the hope is that you and XWW will be able to work out whatever needs to be. And that is how it SHOULD be and what creates the best outcomes for the KIDS. What's in writing is what everyone has to adhere to if you and XWW CAN'T work it out between the two of you. (ETA: So, if your custody plan says you get the kids every Saturday, but you get a job that requires you work Saturday, you two can agree - preferably in writing - to a revised schedule.... but know that at any time, your XWW could say she's no longer willing to do that, and you are back on what's in the ORIGINAL custody plan. Now, if that were to go to court, most judges would not be happy about it if mom agrees to a change in writing, they follow the new custody for x period of time, then mom unilaterally wants to go back to the original plan. However, if after the change in custody, one of the kids starts having problems or acting out or grades drop, etc. then a court may see it as OK)
One thing I would really encourage is a means of communication outside of the kids (using kids as messengers is an AWFUL thing for the kids). There are lots of online programs - they may or may not be available free or via your court. I would check them out. If nothing else works, you can create a shared Google drive that is used. In the old days, folks had a notebook that went with the kids (pref with a lock). You can put receipts that need reimbursement, notes about anything important, etc in there (eg here's the bill from dr smith, which you owe me for 1/2, and Ms. Jones called me today to say that Johnny has been acting up in class. I think he and Jimmy got into an argument about Star Wars, but it may be something else). You get the idea. If you have to talk about things, do it from work or when the kids are not with either of you (kids are smart and super good listeners when they want to be).
As to $ and reimbursement, you need to CLEARLY spell out where they get their health insurance, who pays the premiums, what happens if that parent loses their job/health insurance, who pays for visits, and if out of pocket costs are split 50/50 how long the paying parent has to submit the bill for their reimbursement, and how long to be reimbursed. You don't want to get a $200 bill a year after the kid was in the ER with a demand it be paid next week. Same for school activities, etc (if Johnny is gonna play soccer, who pays for the uniform, the fees, and all the other stuff that comes with a sport?). That kind of stuff can create a lot of post-D tension/conflict, so putting that fall back position in writing now can save arguments later.
Same thing goes with signing kids up for stuff. If Jane wants to do gymnastics that costs $100/month, can mom just sign her up and expect you to pay? No. Those things should be done with other parents WRITTEN consent. And that written consent can be as simple as a text ("hey- exw, Jane wants to do gymnastics at the YMCA. It's $75/mo. Are you ok with that?" is totally sufficient - just screenshot the text to your photos and upload it to the cloud). And what happens if you want Johnny to play soccer, but mom wants him to do cross country? How would that be worked out if you two can't stand to even speak to each other?
And all the other incidental expenses that kids incur, esp clothing. I've seen cases where the parent paying child support did not believe they had to buy their kids clothing. Stuff like that will get most judges pretty PISSED OFF. It's not necessarily something to put into writing, but it IS something to consider and see where you and STBX end up (keeping in mind that just bc you two are relatively sympatico today, doesn't mean that will be true in a year or 10).
As to college, if your kids are still 9 & 7 (ie elem school), I'd prolly not include it at all. In the old days the "default" was usually that the parents agree to split the cost UP TO the cost of in-state tuition at xyz state college. Either parent can obviously choose to pay more if the kid goes somewhere very $$$... or not. If it just says we each pay 1/2, then what if the kid chooses to go to a super expensive school, and doesn't have their act together to get scholarships and the other parent (in your case, mom) says - why yes, Johnny, you can go to HootiePatootie U, cuz your dad agreed to pay 1/2 of any college, but your income has not kept up with college costs (and whose has?). I think including college is something seen more often in high income families... JMO.
holidays - make sure that EVERY holiday that's important to you is spelled out, with the times and WHO WILL DO TRANSPORTATION - eg mom transports kids to dads every xmas eve by 4pm, and dad will transport kids to moms on Xmas day by noon. If you have particular traditions on particular holidays (eg we ALWAYS go to my parents on xmas eve), then I would fight to keep that as the status quo (and vice versa - if you as a family ALWAYS went to XWW's parent's on Thanksgiving for a dinner at 4pm, it may be that you get them in the AM to have a morning "event" [with new traditions] and then they get to her parent's by 2:30 or something). Bottom line is that kids should not have to forego their own traditions bc their parents are D.
As to relocation. I'd be surprised if NJ didn't have a relocation plan/language/laws (do they not already have form separation agreements and parenting/custody plans? If not, you may need to get an atty to make sure you are covered). If not, you could look to other states for language (knowing it may - or may not - be respected in NJ). As I understand it, in most states the general rule is that NO ONE gets to move ANYWHERE w/o prior WRITTEN notice (often certified mail, return receipt) at least 30/60/90 days before the move. Then the non-moving parent has x days (usually 30) to object - also IN WRITING, and maybe to file a motion with the court. In my state (and I suspect many others) this would include just moving into a different apartment across the hall in the same building. Also, in my state, a parent who moves (whether across the hall or across the city or across the country) w/o that notice will (a) PISS OFF the judge and (b) usually be required to give remedial custody time to the non-moving parent, and (c) is usually not allowed to have custody in their new home if it's far away (so if you want to move to Seattle, go for it, but you ain't taking the kids and you will have to come back to Jersey to see them during your periods of custody).
Finally, I thought NJ had a mandatory 1-year separation period. I may be wrong, but it's worth investigating (and perhaps adultery is an exception).
Best of luck...
[This message edited by gmc94 at 2:49 PM, January 14th, 2021 (Thursday)]