Dd14 question for Grandma

My step Grandpa died 2 years ago (88 and served in Vietnam) my mother has lived with them for the past 8 years or so and did all the paperwork to keep my Grandmother in good financial health.

It took my Mom along time and hours on the phone over weeks to get this "dd14" to be honest I don't understand much about these things, personally.

My step grandpa's daughter just called asking for the form, for benifits and such.

My mother and grandmother and nervous to give her this paperwork. They are fine to give her the paperwork but are afraid they will lose benifits if they give her a copy of the paperwork and she changes the beneficiary from my Grandmother to her.

If it matters, my Grandpa died at 88, my grandmother is currently 88 and my grandpa's to biological daughters are in their late 50's and early 60's.

Thank you all for any help.