being uninterested in hay isn't a thing for normal healthy piggies. They will pick through it and only pick out the pieces they want to eat, so you then need to give them more. . they won't eat every single strand all the time, they forage and only eat the bits they want, so you give them some more. dont reduce the amount you give them.
5 minutes is not bonding. the boars needed to be in a bonding pen for several hours to go through the stages of bonding before being moved to a thoroughly cleaned out and neutralised enclosure for them to live in. it then takes a further two weeks of being together to fully form a relationship and hierarchy. you need to make sure all hides have two exits and that there is at least one hide per boar. you will need multiple of all other items - bottles etc. scattering feeding is advisable for teen boars as it prevents food hogging and ensure you have more than two hay piles. you need to respect their hierarchy and handle the dominant boar first. as mentioned yesterday, you then need to plan for what to do is their relationship fails when the baby hits his teens