I would have ensured I wormed and fluked when they returned to prevent them bringing in resistant worms from elsewhere …. too late for that however so yes I would worm (but not with white wormer) Don't see any reason why you cant treat with mineral drench at same time …. unless anyone else knows different?
Some people say the mineral isn’t absorbed as well if it’s given along with wormer. But Carrs’ Animal Health mix a range of their own wormers-with-minerals (both straight wormers and combined wormers with flukicides, and I think straight flukicide with minerals too), so it’s certainly not a definitive rule.
I’m assuming when you say “wormer”, you mean flukicide or combined wormer and flukicide? Otherwise, unless it’s been really mild where you are, I’d think it more likely to be fluke than worms at this time of year, so not sure a straight wormer will help.
Which said, assuming the drench is appropriate, and given all the factors, especially that you don’t want to fetch them in again before lambing, I’d fluke and mineral the two.
By the way, the wily old Cumbrian farmer who taught me so much used to give minerals first, then flukicide a couple of days later. He felt that a sheep which had a significant fluke burden would be so pulled down the flukicide might kill her, so he’d give the minerals first to give them a boost, and then the flukicide when the minerals had had a couple of days to give them that boost. That could well be a hangover from a time when perhaps the meds weren’t as good as they are now, but I just thought I’d share it.