Hi Honey,
Many ((HUGS)) these guys are on 'cahoots' eh?
WRT your 5 year old, as I have one also, I can tell you that sleep has been very changeable and strange for us lately. He is swinging between anything from 10 hours to 1 hours, and surprisingly he seems to be okay on 10 often! Ugh, I miss those 12 hour nights! There have been quite a few posts lately stating the same thing, so if you want to shift his WU I suspect you may have to suck up the later nights with allowing him to read or listen to audio stories maybe? So that he is still in his room giving yourselves the 'couple' time you need, which is something we deem important in this house. With DS we are getting so many 'call backs' and messing about at BT, and it seems that he is just UT despite busy days at school etc.
Your DS is getting 10 to 10.5 hours just like Sam, and if I allow Sam some later nights, then he seems to SR with a later WU eventually or an earlier night. It's hard to accept these shorter nights, but in this house it results in less stress, as long as he is in his room relaxing.
Maybe try the audio stories for him
Give him the chance to 'self regulate' and see how it goes.
What do you think
x.