Grant infinite use of polymorph (to humanoid only) to familiar?

Question

I am wondering if there would be an option to grant the familiar the ability to polymorph itself into a humanoid form (just like what dragons do), which could be interesting story-wise.

The closes hit I can find is Familiar Spell, which is an Epic Feat. I think that's a target too far away from my campaign.

Familiar Spell [Epic]

Prerequisite

Int 25 (if your spellcasting is controlled by Intelligence) or Cha 25 (if your spellcasting is controlled by Charisma).

Benefit

Choose one arcane spell you know of 8th level or lower. Your familiar can now use this spell once per day as a spell-like ability, at a caster level equal to your caster level. Your cannot bestow a spell to your familiar if the spell normally has a material component cost of more than 1 gp or an XP cost.

Can a carefully-worded Wish or Limited Wish do that? Since it is not actually affecting the familiar's compatibility that much.

Answer 1

Pick a Quasit or Imp Familiar.

Take the improved familiar feat. At 7th level, select a quasit or imp as your familiar. Each is natively humanoid-shaped, and each has a native alternate form ability.

• With quasit, you pick one or two of: bat, centipede, toad, wolf.
• With imp, you pick one or two of: spider, raven, rat, boar.

Your familiar can freely turn into your choices, and so can spend most of his time hanging out as a rat (or whatever).

If you want to make your familiar more able to interact with normal society, get him a hat of disguise. That allows apparent size to change enough for your familiar to easily pass as a halfling or gnome.

Answer 2

As the DM, I will allow it to be achieved via a Limited Wish, Wish, or Miracle for now since becoming a humanoid should not affect most of its skills and won't make it more helpful (actually, less helpful in most cases) as a combatant (most familiars are non-combatant anyway). Nor would it be able to become a face (it won't have enough skill points for that). It would simply make the story more interesting (or more annoying if the PC can't handle it well). As for this use, that polymorph will only allow this familiar to transform into a specific humanoid creature (who's appearance shall be decided at the moment this ability is granted) so that it cannot use this to disguise and will always be the same person.

I will leave this question open to gather any different opinions. Guess there's no any RAW prevents me doing so.