Father's dentures

My father-in-law had his second set of dentures made. However, they don't seem to fit well with his gums (probably because his gums are weak), so he's in pain and can't wear them. He initially had the first set, kept going back and forth to the dentist, trimming and adjusting them repeatedly until he got used to them and could wear them. Now he's doing the same process again with the new ones.

Would it be better to get implants on the three molar and front tooth areas and then use a denture~~~? She finds dentures uncomfortable, so it's quite difficult. It affects her eating first and foremost.

Please give me some information.