Hi! It is worth trying with full intros on neutral ground, but please don't get your hopes up too much. The majority of piggies will stick to their decision once they have made up their mind. In a few cases, boars will go together or at least will enjoy roaming/playtime together.
You can find information on how to best stage an intro and which behaviours to look out for at the top of this section.
Alternatively, you can either consider to date each boar at a good rescue under expert supervision for a character compatible new friend or have them neutered to live with a sow each by an experienced vet with a good track record in piggy neutering in order to minimise post-op complications. This also involves a full 6 weeks post op wait for the boars before thaty are 100% safe to go with a girl (I have the surprise baby from a supposedly safe over 5 weeks boar living with me, just to prove that particular point). The advantage is that cross gender bondings are the most stable. Again, dating at a good rescue will ensure that the chemistry is right and that you only come home with piggies that click.
We have got a recommended good standard rescues locator on the top bar; all rescues offer dating for single piggies.