Melissa,
About your twins...  I work in a level III NICU.  Your mom's experience
sounds very typical.  It is a very stressful enviroment especially if  the
mom has other children at home to care for and lives far away.
This mother needs to be commended for what she has accomplished so far.  I am
assuming she has been pumping for 7 weeks, healing from an emergency
c-section, dealing with 2 sick premature babies, maintaining a home and
caring for 2 other small children!!   Most women with c-sections should not
even drive for 6 weeks so how has she been getting to the hospital?  Probably
sacrificing her own health to be with the twins one time a day.
 I have found mothers with babies in the NICU have a different opinion about
bottle use than mothers of healthy term babies.  This mom may feel that a
bottle is a lot better than the feeding-tube that was up the babies nose at
first... so she may see the bottle as an improvement and not something
"Yucky".
I think you should start slow with this mom and find out what her goals are.
 She is obviously wants the best for her babies with consistent pumping for 7
weeks for twins!!  You didn't mention if the twins have any other problems
associated with their prematurity.  It is very likely since they were born at
27 weeks.  Their adjusted age 7 weeks later is only 34 weeks.  These babies
are going to require frequent follow up with many specailist so exclusively
breastfeeding  at breast may not be this mother's goal immediately.
You say she is "laid back" but I would guess she's scared to death.  The best
thing you can provide for her now is constant praise for what she has done
and lots of encouragement.
Good luck.

Sharon McNitt, RN