Hello Laura!
Re dummies.... To get them to replug themselves I would put the dummy back in their hand not their mouth and also do the same when putting them down. I also filled the crib with dummies and put them scattered down each side of the crib so that wherever they were in the crib they could find one. And I used those breathable safety first cot bumpers (can't remember the proper name for them) to stop the dummies falling out of the crib.
Re night feeds... Are you trying to get rid? If so I would start to dilute them until it's just water, then only offer water if they don't resettle with their dummy. Very soon they won't wake for the water any more at all.
To feel confident that they are taking enough formula during the day so that you can start to eliminate the night feeds I agree with your plan of sticking with four formula feeds (one on waking, one after each nap and one before bed) for now. You'll know when it's time to drop a feed because they will consistently refuse or take less than 3oz.
It's difficult to tell what the early wakings are about but for me it ended up being a sign that total daytime sleep needed dropping ever so slightly. We also do 6.30- 6.30 day and I just want to show you what our day looked like a month or so ago when we were also still doing four formula feeds and two naps (now we do two naps and three formula feeds).....
6.00-6.30 wake up and offer 8oz formula
07.30-8.00 breakfast
08.30-09.15nap (earlier then bw recommends but I preferred an under tired nap of 45 mins compared to an overtired nap of 30 mins and I wanted a longer pm nap)
09.30 8oz formula offered
11.30 lunch
12.30-14.30 nap
14.30 8oz formula offered
16.30 dinner
18.00-18.30 as much formula offered as I could get in them! 8-10oz usually!
If I wanted a 18.30 bed time I always woke them from the second nap at 14.30... They just slept better after a four hour awake period before bed time. If I'm right I Think this fits in with school run for o?
Any wakings during the night were settled with dummy, water, pick up put down... In that order depending on whether things escalated.
Hope this helps but do let us know where you're at now with it all as I'd like to help you try and tweak things as you need to...
Lots of love
Xxx