Yeah, I would want to know ages but that's usually not possible. At around one year or so the robo starts slowing down. It's from baby to one year mark that is the most fun. I'd say not to adopt the mother and daughter but to keep looking.
Sorry your other contact didn't work out. Probably for the best as you wouldn't know their genetics with all the brothers and sisters mating. But then unless you buy from a breeder who knows what genetics and health problems you hammy has.
Can you buy two from a breeder even if it takes awhile?
If you decide on the Mother daughter pair they won't be as much fun IMO
But totally up to you
Edit: I have Angel, who is an adopted rescue robo from 6 weeks old and she's now 4 mo old coming up on 5 I think but she has NEVER taken a treat from me. I sse a lot more of her as she hangs around the cage sometimes but if I were to put my hand in there she runs quickly away.
So she was abused as a baby is my theory because the white robos are absolutely adorable. I won't buy a robo from a rescue again. I'd have to be VERY careful which animals you adopt as rescues because I also adopted Izzy from the SPCA and she hides all the time. I've gotten used to it.
The only good rescue I have is Heaven, my Syrian. She had a cuddly sign on her cage so I adopted her.