Best practice for customising Payload while keeping it upgradable?

Hi all, I jumped in last weekend and I'm absolutely loving it but ... I'm customising collections - ie, I've added tags to Posts, and roles to Users etc. But obviously this isn't ideal because when I need to upgrade ...

Given the lack of genuine inheritance in js, what's the recommended way to do this?

'm happy to have my own models (ie a sort of myPosts instead of Posts etc), but what's the best way to do this? Is that what the deepmerge utility is for - to overcome the problem of shallow copying via the spread operator - or is that only for fields?

I also noticed this but can't find anything else about it yet (ie, tutorial, or help page etc - I appreciate it's newly added of course) -

Would welcome any ideas or pointers on how others are doing this. Thanks

I just realised the flaw in my thinking... payloadcms itself isn't the post, media, etc collections is it. That's the blog demo/template. So updating payloadcms itself - as opposed to any improvements to the template - won't affect that code or any code I change in the template files. Sorry, silly mistake 😉 Really loving this platform so far! Thanks