how old can a maltese be & have puppies

Question
I have a grandmother maltese (12 yrs), mother (10) and "baby" Princess (~7) and a friend with an 11 month old male maltese. I am not even sure she still goes into heat but we would like to breed them.  Is she able if she does go into heat? Would the 10 year old also be able to? They are very energetic and healthy.  Any concerns? Princess never had puppies so far.  Thank you for your thoughts/info.

Answer
Why would you want to breed them at this age? This is the same as a sixty to seventy year old woman having a baby. Do you really want to do that?? I;m sorry I can't advocate that at all.
It's very dangerous to both dogs, Your seven year old female who has never had puppies is also not a good risk. This is about the same as a woman in her late forties having a baby. Pass on this, for your dog's sakes,
Good luck
Cindi