Switching feeders....

Alright so I have 3 snakes that are apparently mice eaters. One I already knew about since I've had her for just a few days shy of 9 months now. The other 2 I just picked up 3 weeks ago. The first time I fed the new guys I only had mice available cause where I get my feeders till my rats get going only had large rats. The second time I tried small rats(maybe 5 weeks old) for my larger 2 and a rat crawler for my first girl. Everyone showed interest, but refused to eat them. Ok no problem I figured I'd try again this week..... Still interested but not eating.
My first girl cuddled her rat pup! the closest she came to killing it was when I went to remove it after an hour of nothing when she sat on top of it. I know she has it in her to take a rat because she did it for me twice about 6 months ago no problem. I think they might have been a little big or she got nipped, and it put her off of them? Since then I have tried scenting a rat in mouse bedding.... Nothing. Offer a small mouse followed by a f/t rat pup for 2-3 weeks, and then an appropriately sized rat only..... Nothing. This snake will also only take solid white or 90% white mice.
As for the other 2 I haven't tried anything but to offer the rats yet. I don't have any mice on hand, and didn't think to try asking for used bedding today while I was at the shop. All husbandry is spot on, so not concerned there.
Any added advice you can give is greatly appreciated.

Switching can be as easy as one feeding and as hard as months of trying.

Tough love is key in most cases but of course this require your snakes to be an appropriated weight.

Easiest way to get started is to switch a a rat the same size than the mouse previously offered (size can be intimidated), once the animal east 3 to 5 rat consecutively you can up the size as needed.

It can take months and during that time do not feed mice otherwise you start all from zero again.

Most will switch even if it take time but be prepared that some may never will. (rare)

The only mouse I plan to get unless someone starts too loose too much weight is for scenting the rats. We just got a scale last month, so I can monitor the amount of weight lost which is part of the reason I'm seriously attempting the switch now. At what point do you worry about how much they loose, or do you go by the look of the snake in question? My 3 range from 400+ to 1200+ grams If that's any help.

I recently got two mousers back on rats. I have not found scenting with bedding to be of any help. I have only had success scenting F/T rats with a F/T mouse. I have found that if they are a little bit damp, not wet, but with a little bit of condensation from thawing etc. on the fur, the scent transfers better when I rub them together. Then I used hair drier to heat the scented f/t rat up and it gets dry before feeding. But I have in the past rubbed together a dry mouse to a dry rat and it did not work for me.