We go to a big family gathering at DP's dad's house (my folks live overseas). When there's card making etc at playgroup, DS makes a card for his Pappa.
He's only 2.5yo, but he knows he doesn't have a daddy. He tells me "Naomi/Ed/etc (insert friend's name) mummy daddy, DS mummy ima".
I am happy he has a few great men in his life as role models and people he can celebrate father's day with.
I'm interested how other gay mums do (or don't do) Father's day.