not sure how this will work as both Sites import their own settings and styles that are quite unique.
You could try:
1. Install Niche. Go to Customizer > Additional CSS and copy out the CSS for safe keeping.
2. Make a change to the site, this should stop the next import from removing Niche. Eg. Remove Home Page if thats not required and add a test page.
3. Install the Mason Site. See what happens.
You will need to check the Customizer > Additional CSS to see if the Niche CSS is still present if it isn’t then paste it back in.
Thanks for your fast response. This sort of worked. In the end, importing Mason messed up a lot of things in Niche though. I ended up just importing Mason, exporting CSS, restoring to before the import, import Niche, and add the few CSS lines from Mason on top of Niche’s (the non-conflicting, which were most). I’ll design the navigation manually to look like Mason. Still saved lots of time compared to importing Mason and trying to set up the store as it is in Niche!
Thanks again and have a nice day!