2 different Iphone same Icloud emails

Hi all,

My grandparents have 2 iphones, one Ipad and the same email.

MY GrandFather had to do a backup on Icloud for his Iphone.

Everything went well, but the after he recovered all the data, on the Ipad and Iphone of my GrandMother there is a red dot in the Options that says :

You have unsyncronized data in Icloud. Syncronize it now.

Now my GrandMother doesn't want to syncronize the data because she is afradi that she will loose all her data and have the data of my Grandfather that are in backed up in Icloud.

How to get rid of it?

Syncronize the data is safe for my Grandma's data?

Thanks a lot