There are a few dozen of these Compact Jazz release groups which I’m trying to add to this series (I’ll fix the kludgy disambig once the other series goes away).
The only ways I know to do it are the relationship editor for the series, which is tiny and awkward, especially once you’ve already added several, or going to each individual release group and editing that, which is even less appealing.
I do tasks like this by opening multiple Browser tabs - one per release. Then make the most of keyboard shortcuts in the browser. It means short repetitive punches of buttons.
Bulk work is just boring and tedious unless a script is written for it.
It would be nice to get a “Make Series from this Search result” type option.
You go back and forth from tab to tab with keyboard and repeat:
From your RG search page tab:
In your RG series edit page tab (where you have already focused the Add another release group link in the relationship editor part):
That sounds like about as good as it will get