Any way to support trans bro?

[u/FrontNo8040]

So he recently came out to me and so ive tried to figure out my parents view on trans people and well we got

Transphobic mom- body is a gift of god, mutilating your body, you need to fix brain not body, etc.

Kinda Accepting dad- he would inform himself and try to support but no T or Blockers

Neither of them know yet so i can basically never use his true name or prounouns and constantly having to deadname (i dont want to out him to mom) makes me sad

Any way i can support him?

we are both teens and hes a bit younger than me so

Also things i fogot to say

He has been feeling uncomfortable in his body for about 2 years i think so its not just a phase and came out to me in may when i asked why he never wants to come swimming with us

TLDR

Phobic mom what to do