Sandy,
Can't address the relactation question, but I had a mom who adopted a
baby from China about 1 1/2 years ago.  She was still nursing a toddler
and hoped that by pumping she could "pump up" her supply for a little
one.  The baby she adopted was about the same age your mom is talking
about--around 3 months.  What my mom found was that these babies are fed
a propped bottle of rice based milk--it's thicker than milk--and her baby
was not interested in the breast AT ALL.  In fact they had a hard time
just getting her used to being held and drinking a "liquid " formula.
Mom had nursed 7 of her own children and was determined this baby would
get the same milk as the others.  But after about a month of pumping, she
gave up because the baby was not much interested in the breast milk
either.  I think they used a soy based formula for their baby, not a
dairy based one.

By the way, tell your mom if she is taking the pump to China with her to
check with the pump company for an electric power adapter, because the
current or something in China is different.  My mom took a Nurture III
with her so she could keep pumping on the trip and the motor died in just
a few days. We didn't know about getting an adapter. It was the first
time I had had one of their motors go in over 5 years of selling them.

Pat, LLLL, IBCLC
Avon Lake OH