add existing audio to selected tracks

After trying out ardour several times in the past, I finally started my first project with it.
A really great feature is the possibillity to add many audiofiles in sequence to a new track automaticaly. My audiofiles are all sorted after location and recording time. (->rightclick to any audiotrack/‘insert existing audio’/‘as new tracks’+‘at session start’+‘sequence files’) I use one track per location. At one location there where almost 300 files, so you can see how much I apreaciate this function.
Now ist this a work in progress and there are frequently added (sometimes many) files to the region list. And here is my question

how can I add many existing audio files as a sequence to a selected track (insert at playhead)?
The feature “add files:to selected tracks” disappears when more than one file is selected. This makes sense when the “mapping: sequence files” is not selected, but it should be possible to add a sequence to one selected track.

Thanks
Klaus

I want to add that ardour (version 2.5-x11) allways breaks down when I try to remove one track. So importing audiofiles as new tracks, moving the regions to an existing track and finally delete the new tracks is not an option.

Edit: it works, when all audiofiles and the right settings are selected in the “Add existing audio” window (the files to import selected, ‘insert: at playhead’ and ‘mapping: sequence files’). Then click ‘cancel’. After again choosing right click and ‘insert eixsiting audio’ the function ‘add files: to selected tracks’ is finally automaticly chosen.