I keep out of the way as much as I can when overseas Grandma manages to visit, and when we are all together, I make a big effort to take a back seat.
I am the lucky one, the one who normally sees dgd several times a week, helping out with childcare. The other Grandma, my DiL's mum, can only visit about once a year, so really needs this time to build a proper relationship with our dgd.
I can see how it must hurt to suddenly feel relegated in your dgd's affections, but it is only for a short time. Try not to let it show, and just go with the flow.
Remember that she is nearly a teenager too, so her affection for you (and for other grandma too if she was around more) is likely to change soon anyway.
If you have always been close, just carry on being you, and you will hopefully come through it with a different but more mature relationship, regardless of how well she gets on with her other grandma.
Army horses loose on London streets