
you mean she was a single mom when she had her son ? and her son has her surname, is the father mentioned on his birth cert ?
now she is married to a brit, and here on a spouse visa ?
i don't know what your thai friend is talking about, the 2 to 3 yrs might be about, she needs to be in the uk at least 3 years to apply for citizenship and get a british passport, but that has got nothing to do with bringing her son here..
she could have applied for a settlement visa for him, as her dependant when she applied for a spouse visa.. and she can apply for a settlement visa for him anytime, she needs to gather evidence for his app thou..
but she must do it b4 hes 18, or he has no chance of being able to live in the uk with him mom,
whats he doing now ? is he still at school or working ?