Change UID/GID asterisk identifiers and permissions

Hi good morning,

I have one app install on a server which is communicating via NFS with asterisk server.
This app read/write/execute directories/files on /var/lib/asterisk/voicemail.
When this app create directories/files it uses a different UID/GID with respect to asterisk UID/GID.

If I cant change the UID/GID which is using the app, anybody knows If I can change the UID/GID which is using Asterisk? How can I do it? It would have repercussions with another thing on the asterisk server?

Thanks by your help