What's right for a 2yo and 4yo?

ldoo

I have two girls. One just turned 2 and the other will be 4 in a month. I've suggested that they have time with their dad Wed.-Thur. from 5:30-7:30 and all day Sunday.

That's what we've done for a month, and it's worked out well.

Their beds will be set up this week at his house. So overnights will begin soon.

Conceivably, they'll start spending the night soon Wed. and Thur., and then Sunday night. 

What do you fine people think? Is that a healthy schedule for that age group? Or am I actually giving him too much overnight time with them at this age?

Any opinions are much appreciated! I want to do what's right for them and not get sucked into HIS rules for how he thinks it should be.