Hi Taco,

Do you talk about Saved addons or custom ones, coded by user?

If Saved read here, at the end >> https://www.joomshaper.com/documentation/sp-page-builder/sp-page-builder-4/export-import-and-save-for-later-use

you make 1 row of 3+3+3. in the first you put a text field. and below that you want for example an img. in the builder 3 you could say ad addon under the text field. hope a little clearer

Do you want to add more then one addon inside column? Am I right?

yes

So yes, It's possible,

Mark column where first addon is, add new addon from the list, and there 2nd will be added under.

Later from Layers tab you can move up/down addon