You will want to look into using the Attribute Manager to transfer your attributes for the new template into you old one.
Be warned it can get very messy depending on whether you 'Overwrite' or 'Append' the attributes.
'Overwrite' will replace your existing attributes - maybe not what you want if you have customised them to suit your needs.
'Append' will add all attributes as new ones but you may end up with a lot of duplicates that way.
I could probably write a short essay on Attribute Management (but I'm not going to!) as there are many posts in this forum that talk about them.
Always make sure you keep a copy of your original file just so that if you get into trouble you can trash the changes and go back to what you had before.
Barry.
One of the forum moderators.
Versions 6.5 to 27
i7-10700 @ 2.9Ghz, 32GB ram, GeForce RTX 2060 (6GB), Windows 10
Lenovo Thinkpad - i7-1270P 2.20 GHz, 32GB RAM, Nvidia T550, Windows 11