Hi Ana,
The very function of the group/list column is to control between-subject row selection. All rows that should be presented to the same participant, even those defining different conditions as a result of a within-subject design manipulation, should have the same value in their group/list cell.
The part of your table that you posted suggests another between-group manipulation that does not match the values in tipo_DP: all participants in group 1 (A) will only see pl-sg-sg rows, 2 (B) will only see sg-pl-sg, 3 (C) will only see pl-pl-sg and 4 (D) will only see pl-pl-pl. Because group starts over in the elidido rows, participants in group 1 will also see the E rows, 2 will also see F, and so on.
So there is no group of participants who will see all A-B-C-D rows, and no group of participants who will see all E-F-G-H rows. What you have is four groups of participants: group 1 will see all A-E rows, group 2 will see all B-F rows, group 3 will see all C-G rows and group H will see all D-H rows
If you are satisfied with the between-subject assignment of the crossing of num_DP-num_poss-num_NouPred as currently defined in your table, but want to additionally have tipo_DP as a between-subject factor, then it means that you effectively have 8 groups: your table currently defines four levels resulting from the (non-exhaustive) crossing of num_DP-num_poss-num_NouPred, and two levels for tipo_DP, which results in 4*2 = 8 groups. So starting from the first elidido row, you could have group jump to 5, 6, 7 and 8 instead of 1, 2, 3 and 4.
Does it all make sense?
Jeremy