I wouldn't use elec tape or put the 2 foals separate from all adult company at first round, but each to their own, places have their own options and limitations depending how they're set up. Whatever works for the ease of handler and least stress for foals and mares.
The way I used to do it with 2 or more foals was to swap mums and foals over (ones that have already been running together during summer). First in a barn with gate between 2 pens and a bale each side of it so all 4 were eating beside each other but no milk exchanged. Then moved the next bales across the pens so plenty talking space at the gates but to eat they move away rather than toward. And so on from there in easy stages til foals were all together with older youngsters/ponies and grass while broodies were on rougher grazing to dry off faster.
With just one foal I twice decided to leave it on until the next foal, allowing self weaning. The foal has got to know other ponies over a fence which s/he then looks to for company. Opening the gate is usually enough to bring the youngster running and Aidan's their uncle, Briagh and Rowena their granny, and the rest fascinating new friends to torment..
I would always leave a 'nanny' mare in with foals and youngsters once they were all together, ideally an older experienced broodie not one of their mums.