resolve.conf search domain

When I use DHCP with a MAC address reservation I see the search domain in my resolve.conf file

root@plex:~# cat /etc/resolv.conf
# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
#     DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
nameserver 192.168.70.1
search local.lan

This allows file mappings through autos to work such as

Movies    -fstype=cifs,credentials=/home/media/.smbcredentials ://fs01/Movies

When i convert to a static address and duplicate the settings over with dietpi-config, I lose the search domain being passed from my DHCP server, i.e

root@plex:~# cat /etc/resolv.conf
# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
#     DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
nameserver 192.168.70.1

This results in file mappings don’t work anymore. Should this be exposed in the dietpi-config menu or is there a official linux-way to handle this I don’t know about - or should I be using the full extension. Sorry if this is an obvious Linux thing - Im new here!