Also are they being worked?
My friend had an issue which left a huge amount of her land unsafe for about 14 months. 3 ancient septic tanks were involved but they turned out to be only the tip of the iceberg. Long story.
This left her with at best 2 useable acres and 12 horses and ponies sharing them, several of whom didn't get along. It was hell.
But the majority of them were actually surprisingly fine as they were used to teach riding and driving lessons so were in and out much of the day, hacked out on their days off. The liveries who could move out temporarily did so leaving her with 7.
Some creative use of electric fencing, to separate the dickheads from the ones who wouldn't stick up for themselves and rotating the ones due to work soon into the 2 hard standing areas helped and the ones we trusted not to leave the property or create trouble were allowed to wander freely around the yard and graze on the unfenced patches of grass and cow parsley.
The ones who could not be trusted not to piss off up the drive and into the sunset, got taken out to hand graze between lessons and everyone stayed in at night.
It cost a fortune in hay and enrichment toys to keep them occupied and you couldn't miss a day's exercise or they'd be climbing the walls. But being in full work made all the difference. No one starved, no one fought, everyone was reasonably content except the humans.
So it was doable. Not an ideal situation, never fucking again by any means and certainly not permanent but I think 2 smallish horses who get along and are in full work, sharing 3 acres would be fine.