It goes something like this
DD aged 2 has a good night with no crying or getting up but gets disturbed by baby brother.
DS aged 4 mnth looks like he's gonna sleep through (no noise before 5am) when DD gets up at 5.15 and gets very upset when told it's too early and to go back to bed, disturbing DS in process!
so frustrating it's either one or the other, never neither - I don't suppose anyone has any suggestions as I certainly can't think of any??