Hugs, hun.
Most often the "offender" :-) goes into the swing where she will usually fall back to sleep. I don't like using the swing, but i have tried shh-pat and have not had any success.
I wouldn't feel bad about this at all. at this point I would use AP that works to get more sleep into them. I struggled so much with ST just one baby, so I can only imagine doing Shush-pat with 2... I did find with mine that as he grew older it was easier and easier to do ST and he responded well to it when he was around 5-6m. Before that I would let him sleep in the buggy, 'cause that's where I knew he will have a good full nap.
We are planning to transition slowing moving 15 minutes every 4 days. The girls are struggling to stay awake for the extra 15 minutes so far. Yesterday (Day 1) was pretty good, today (Day 2) has been very bad and it's only noon (all three of us crying after the first very short nap).
It sounds to me like the 45min naps are because they *are* ready for the transition, which basically mean they are ready for more A time. It sounds like you are already working on that, but I'd be a bit cautious with increasing the A times. Some babies find the 15min jumps too much and need smaller jumps, like 10 or even 5min.
If you do only 5 or 10min jumps you have a better chance of preventing them from getting OT because you give them more time to go through the transition.
Until they are with higher A times and will start to nap longer (which might take a while) I would do like Laura suggested, I'd offer more short naps during the day so they don't finish it OT.