Use the dropdown menu with multi-value tags

So, I made a big list of user-defined genres and i want to write them using the dropdown menu. It's possible if the song has only one genre, but how I can add multiple genres without typing it manually?

In the GENRE field genres are written with separator so the dropdown won't show since there's already text in the field. I can use alt+T to open All Tags and see genres separated, but I can't use the dropdown in All Tags.

Is there any way to add multi-tags with the dropdown menu?

No, but you can use actions of type "Format value" to append Genres to the existing genre.

This way I need to create an action to every genre?

Even with the list, you can still manually add or change any genre using copy/paste or even just typing it in. I don't know of any app that has a drop-down action that allows this choice to be appended to what is already showing, that is just a limitation of that function.

the only idea i have is to add the dropdown to All Tags menu

I use the following solution. If i know in advance, that i want to add more values, first i save the file with empty field (so that the custom list will appear afterwards), then i select the required value from the predefined custom list of the field, and cut it (Ctrl+X), then the same with the next needed value, and so on. Finally i paste them back (Ctrl+V).

To insert 3 or more values, we also need the Ditto application. It is anyway very useful.

On the other hand, i also have predefined Action Groups for entering and removing common values, since, for example, i always enter the Carib value after Calypso, or the Latin value after Tango, Bolero, Chachacha and so on. Example:

Genre#Add (to the end)#Latin

Merge duplicate fields "GENRE": "/"
Format value "GENRE": $ifgreater($strstr(%genre%,Latin),0,%genre%,[%genre%/]Latin)
Split field by separator "GENRE": "/"

Genre#Remove#Latin

Merge duplicate fields "GENRE": "/"
Regular expression: /Latin|Latin/ replace with nothing
Split field by separator "GENRE": "/"

You could shorten that set of actions to:
Format value for GENRE
Format string:$ifgreater($strstr($meta(genre,0),Latin),0,%genre%,%genre%\\Latin)

Thank you, ohrenkino. Yes, you are probably right. But i wrote that Action Group BEFORE this problem was solded. The problem came back once, and i think, it might happen again. This Action Group with 3 actions does not run long, and i use it typically only for one or a few files at most.