Hi K., I am writing to you from the perspective of a stepmom to one of my 5 kids. My stepson was 6 when my husband and I got married 5.5 years ago, and since then we've had 3 more boys (including twins), and a girl. My stepson never new his parents as being married, so going back and forth is all he has known. My husband and my son's mom have 50/50 and it has worked well (with challenges sprinkled in between). 50/50 doesn't necessarily mean you have to do week on/week off though. Although many of the so-called "experts" seem to think that it is best for the kids. In my experience it is good have some flexibility, and when the kids are as young as yours are they do better when they get to be with their parents as much as possible. From what you have written it sounds like your ex is probably a good dad who loves his children. It is actually a good thing that he wants to be with them because he misses them - if he didn't miss them then you'd have to worry... My stepson's mom is also remarried so he has the benefit of 2 very loving homes - he sees it as a good thing! Are there challenges and difficulties that come with going back and forth? Absolutely. My husband and my son's mom communicate often via email when it comes to scheduling, school work, etc. Communicating over the phone isn't very productive. Anytime he is sick and its his days at our house he usually goes to his mom's - because as a mom you are the only one that can really make them feel better. :)
I would encourage you to do the 50/50 - although it is hard on you as a mom - because you will miss them when they are gone and worry that they aren't getting to bed on time etc.
Here are some schedules we have tried over the years: Every-other day and alternating weekends (this was used when he was ages 1-5). At such a young age I think this worked because he didn't have to go too long between seeing either parent. Once he got into school we tried the week on /week off schedule which was too hard on everyone. My stepson really missed his mom when he was at our house - which is normal a child's love for their mom is much different than dad's. Even with my other kids they miss me when I'm in the next room or go to town alone! At that young age they do need mom more, but in the situation you are in they can benefit from developing a relationship with their dad now. One schedule that worked really well was 2 days on 2 days off and every other weekend. This was great especially when he was younger. Yes we had to communicate about homework, games etc., We tried the week on week off a second time once he got older - with a one day/overnite visit in the middle of the week. This was okay. I think that the schedule we have now is by far the best one - or perhaps it is the best one for the stage he is at. He's with his mom every Mon/Tue, he's with his dad every Wed/Thu, and we alternate the weekends.
I would imagine, from your ex's perspective, that discipline and keeping to the schedule your kids are used to when they are with him would be a challenge. Why? Because he wants to spend as much time as he can with them. To him it is probably more important to stay up a little later just to be with them. Is this right or wrong? I would venture to say that if he and his wife shared custody of the kids with you and your boyfriend then your kids would have an appropriate bedtime, get homework done etc. There is always a "transition" period of about 1-2 days when my stepson comes over, and when he goes back to his mom's. We all know and expect that - so we cut him a little slack his first day back. But by day 2 its back to the routine. When it comes to vacations etc. both sides are flexible as well.
Also my stepson's school is closer to our house than his mom's but that hasn't been a problem. And as a stepmom - his dad handles most discipline. I am not his mom - he has one - and so my relationship has been unique to us. So your ex's wife will have to figure out her roll as a stepmom. I do some discipline when his dad isn't around (honestly he's such a good kid that it is very rare anything has to be done).
My stepson, until recently, doesn't take clothes back and forth. We buy him school clothes that he has here, and he has stuff at his mom's. Now that he's 12 he's starting to care a lot more about his apperance so sometimes he coordinates with his mom to drop off his favorite pair of jeans etc. Now that he is getting older he is needing mom less and mostly wants to hang out with his friends.
So in a nutshell for the benefit of your children give them the opportunity to have equal time with their dad. Because before you know it they are going to be in Jr.High and influenced by all kinds of people and things. It is worth a try to do a 50/50 schedule for a trial run - then get it in writing with the court after you see what works best. I think that the worst thing is to put the kids through mediation with the court.
I have had "advice" from people on the outside of our situation say as you did that he would do best with mom the majority of the time. I can only see that as being true if the children were being neglected at the other home. But if both parents can provide loving environments then the children will thrive from receiving love from both biological parents. Believe me, the love I have to give my stepson, is not the same that his mom can give him - especially if he's had a bad day.
I hope this is somewhat helpful to you. All the best! And I hope you'll let us know what you decide.