Yes, a benefactive such as "for my mum" behaves like an indirect object, in that it can often appear before the direct object without the preposition:
I baked my mum a cake.
She sewed me a shirt.
But this is not natural for all verbs, and I'm not sure what rule will predict it. So
? He dug me the garden.
does not sound right to me whereas "He dug the garden for me" is fine.
I think the availability of this construction depends on whether the actor ends up providing an object rather than just a service to the beneficient, but I'm not sure. Consider
She painted me a picture.
which is fine, but
? She painted me the house.
which sounds odd to my ear.