Adjusting infants sleep routine to accommodate out of home in witching hour

I am a single mum of 2 children. 7.5 mths & 24 months. I've always followed my children's lead & organised my days around them. We've employed a "flexible" routine, which with the occasional disturbance, the kids bounce back.

24 mth wakes consistently at 5am, and wants bed around 6ish & asleep by 7 (wind down ritual etc).

After almost 12 mths absence dad renters the kids lives. Court award access. Dad is very rigid & belief "kids don't need sleep".

Access:

Mon. 4pm - 6.30pm (visit only 90 min, but ive included travel time etc to show where kids out of house)

Wed. 4pm- 6.30 pm

Sat. 6.15 am - 10.15 am

Sun. 9.30 am - 4pm

Please note. In my life these times are immovable & I have no influence over what happens while they are out of my care. Also children spend evening in pub/club environment.

Given children are retuned home at 6.30 & toddler asking for bed usually before that. Toddler has past his "tired signs" and into unmanageable. Baby is BF and wanting attention & bed. Attending to baby, pushes toddler further to unmanageable, and attending to toddler extends baby's "up" period further.

Problem I believe is in sorting out toddler. The struggle to get to bed leaves him overtired & he refuses day time naps. He gets 9 hours per 24 on a good day. Leaving him cranky & unmanageable & hurting sister. Spending an hour or more on the "responsive settling" techniques means I cannot attend to baby & creates baby issues. During "awake" times, toddler no longer able to entertain them self. As baby gets disturbed when I try to feed & bed her, baby overtired & no able to be out down. Creating a cycle of madness which means we cannot get out of house. I get 2-3 hours of broken sleep per 24 hours. Not doable.

My thoughts:
1. Can I adjust the kids routine say by an hour? So toddler would more often than not ask for bed around 7, rather than 6? Meaning juggle to get kids more manageable. How do I do this?

2. Given both children currently wake at 5, how do I sort out the baby's day so that she is going down the 2-3 hours she needs to and put her in the best position so that she is not overtired when I need to put her down in the evening? I think I need to see something firmly as a rough guide (ie down at 7.30 - sleep 2 hours). I understand flexible routines & needing to adjust according to circumstances of day - but every time I look at the puzzle I have her waking about 1pm, leaving her unable to have a nap before dads & realistically about 6 hours before bed. She then doesn't get a good feed & wakes overnight 6-8 times :(

I've just been discharged by Ellen Barron who say I don't have a problem. That I do know how to settle the children. They are focused on responding to children's needs & psycohological impact of children going with stranger. I find that spending 2 hours an evening (every evening) because of disturbance not acceptable.

I see it in my children's the difference between them sleeping and not. Also, with no sleep for me, I am not able to be the mother I want to.

Hopefully someone can give me a "rough road map" to work towards & ideas how to shift the children's evening bedtime. In the kiaos that is our day, I think havig something tangible as a guide would really assist.

Thank you!!