Yes to the first nap Aloha it's exactly the same here. Push the first nap too late and the whole daytime sleep just falls apart.
We've still got 2-hourly wakeups BUT I'm managing to occasionally get him back to sleep without feeding. So last night there was a 4 hour stretch between feeds (although one wakeup in between, teething gel given & back to sleep). So I'm really hoping we're coming through this now!
I've also been introducing a bedtime routine. Previously Z would go to bed at the same time as us, with evening naps downstairs with us. However more and more he was just staying awake in the evening (maybe noticing that his brother was in bed and he'd get undivided attention from us??) despite being tired and just getting more and more grumpy.
So now once DS1 is in bed, I start the bedtime routine for DS2 and he happily goes to sleep (done it 3 evenings so far). His naps downstairs are never longer than 45 minutes, but when I put him to bed upstairs in our bed he goes for longer, so I hope he keeps this up, because I feel a lot more myself when I get some time to do my own thing in the evening!! Dream feed him when we go to bed which goes OK as well.
I try to avoid changing his nappy once he's gone down for bed, but it does mean he looks like he's got a pumpkin under his nappy there are so many boosters. Overnight I put him in a bamboo nappy with two folded up boosters at the front, which just about lasts 12 hours.
We're going on a week's holiday on Saturday to a cottage in Herefordshire. Looking forward to it a lot, although no idea how we'll get everything we need in the car...