Hi Mum, I was so sorry to hear about the awful week you have had.
Yes it is possible to bond boars. I have a new adult boar Gilbert who has been here for three weeks now with our 4yr old boar Murran & all is well. O0
We took Murran along to the rescue & they were introduced there on neutral ground. They were put in the run together with some veggies to take their minds off the situation! They saw each other, sniffed, then carried on eating! They were in the run for about 45mins & all was well. We took them home in the same carry case, but had a spare on us just incase of problems. They just cuddled up together it was lovely.
I had sterilized out Murrans cage (base & bars) along with the dishes etc. with baby sterilizing solution. I places different toys & house in the cage & in different places so Murran definitely wouldn't recognise it as being "his" property. All is fine with these two boys, they are both laid back & it seems neither of them wants to be top pig, they are just glad to have each other as company.
Basically the lady at the rescue knew the signs to look out for if it looked like there would be trouble! We tried Murran with a smaller adult boar there at the rescue aswell but the smaller boy was going to cause trouble so she removed him as soon as the warning signs arose!
There was still no guarantee that the boys would get on once they were home, but if that were the case we had the option then of taking Gilbert back to the rescue. Luckily all has been fine.
You could try you two lone males together. It will need to be neutral territory & if they get along you will need to put them in a sterilized cage if they are going in one that one or the other of them already lives in.
What happened with the males you tried bonding using the tips from barmy4boars?
Hope this helps & good luck with what ever you decide O0