Core upgrade changes systemd unit file- Is there a way to keep my customizations?

[cult_hero13]

I use a slightly customized Splunkd systemd unit file. When I apply a core upgrade to my Splunk installation, I've found that my unit file has been renamed and replaced with what I can only assume is a default one from Splunk. Does anyone know if this is in a template file somewhere? I'm trying to see if there's a way to change it so it contains my customizations.

[cult_hero13]

Correction... it doesn't seem to have anything to do with the upgrade but rather the use of (/opt/splunk/bin/splunk start|stop).  If either of these commands are issued, whatever Splunkd.service file exists is renamed and replaced with a new one.