Thank you again for your kind answer.
I have multiple set of data in "my dataset" (ScreenShot .......0013) , but when I click on WRITE MULTIPLE and select 2 sets (SS 14), then the content that appear is just one of them (SS ....4950).
And if I click on ADD MORE, it appears the list of NEW DATASETS, in this screen I cannot choose MY DATASET (SS 15).
If I choose MY DATASETs>MORE OPTIONS>WRITE MULTIPLE>ADD MORE>[not from MY DATASETS, but from the list of new datasets that appear]eg:LINK..., in this case aI can create a multiple-line tag (see screenshots n° .....16)
Thank You