What a great grandma you are...so concerned and helpful! Your DIL is very lucky to have you
First...an opinion. Pumping and feeding expressed breastmilk, IS breastfeeding. That's my opinion, many will not agree. She's doing her best along with adjusting to being a new mom. It's a big task. The issue is, as long as she supplements with formula, the less her body will make.
Second...can you consult with a lactation specialist? Our town has hospitals that can help. Also, we have a store which supplies pumps, tops, nursing supplies. They offer lactation consultations.
There are lots of good books on nursing. The latch is the key. All I can describe it as, is a VERY wide open mouth, taking the whole areola (and thus the nipple in). The bottle feeding has taught the baby to just suck on the nipple, which will just not work for breastfeeding. It's a whole different action.
The formula thing (at the start) was probably bad (and old-fashioned) advice. There are circumstances when this is called-for, but not many. Babies need VERY little liquid at first, as their stomach is the size of a walnut. I had a c-section on a Tuesday at noon. My milk did not come in until Saturday afternoon. She nursed and probably was hungry for that week, but learned to latch properly etc...as is the natural process. I also pumped, which really helped so someone else could feed her while I rested.
Let us know how it goes. There is a way to get that baby to the breast. Lots of practice, patience and help from her supporters.