Kellymom has some great suggestions:
http://www.kellymom.com/bf/pumping/alternative-feeding.html

I know how stressful this can be. Some of the most common suggestions are to make sure that mom isn't home, to walk with the baby as a distraction, and to keep trying. Sounds like you already knew to try different bottles.

Read the kellymom pages and remember, miserable as it seems, she will eventually learn that the bottle=yummy food.

BlueDevil98, Thank you for the kellymom website. We thought we had tried everything but have found some things to try, such as warming the bottle nipple. Seems so simple, why didn't we think of that. There were other ideas we can try, I'm anxious to get started. It's too late to call daughterinlaw tonite, will give her this website in the morning. Again, many thanks for your response, I'm feeling more hopeful.

Avent bottles are great have you used these??

Awbrey, they have 14 different bottles, including Avent. Thanks for your reply, I appreciate you trying to help. Grandaughter will now eat cereal and vegetables, we're hoping the bottle is next.

I found it easier to just give my last nursling a sippy cup. He would take nothing but my nipple or water from a sippy cup.
You don't have to use a bottle. Anything that they will take to get the nourishment down works.

The AAP recommends solids no earlier than "about the middle of the first year," and for good reason. Babies are not able to fully digest table foods until this time. Best to wait until baby can signal by grasping, self-feeding, and swallowing. (as opposed to exploring and spitting back out!) Some infants with a predisposition to allergies will resist solids and develop beautifully on the breast. Human milk is designed to be the mainstay of the diet throughout the first year of life. Solids are simply added slowly as baby socializes and explores tastes and textures on her way to a complete diet.

Cereal is often a vehicle for artificial iron yet breastmilk is the most bioavailable source of iron she'll ever taste. Flooding baby with artificial iron jeopordizes her ability to fully benefit from antibodies in mother's milk. (There's a longer explanation, but that's the gist of it!) The last thing employed moms is a loss of antibody protection for little ones!

Kellymom is a great site. So is La Leche League International. If there are meetings in her area, your daughter in law will get terrific information and probably some new friends. Evening meetings are more likely to attract employed moms but some moms work evenings so who knows.

Eventually babies take bottles and cups. They are far more likely to accept a bottle from Grandma or other caregiver! This is a relationship Grandma builds with baby -- if Mom is around the baby will hold out for Mom, and can you blame her?! But grandmas and dads have magical powers too!

Here is a link that might be useful: La Leche League International