Dad keeps biting his son

So for context I have 4 dogs in my house (mom 2yo, dad 4yo, and two 8 month old puppies boy and girl). Nobody is fixed yet but Xena (mom) is getting spayed next week. No plans to neuter Loki (the dad) and chef (the son) won’t be neutered until November this year.

Loki has no issues with the girls he lets them walk all over him, but he regularly bites chef when he tries to get too affectionate with him. They’re fine just chilling and even playing outside, but sadly chef gets bit when he just tries to love on his dad. It happens maybe once or twice a week, the worst was a month ago Loki bit his ear pretty badly. It’s fully healed but won’t stand back up (3rd pic). And again this morning chef got bit.

I know testosterone is at play but I can’t really do much about that until November. Having them constantly separated kinda sucks too. Just looking for any advice from anyone who’s dealt with this? Maybe some training or supplements can help? Thanks in advance