You can try something like this in a button in a WORKORDER record:

for woRec in WO-TASK do
    let wrCheck := WR-TASK[TASK-POS = woRec.TASK-POS]
    if count(wrCheck) = 0 then
        create WR-TASK.(
            WORKORDER := woRec.WORKORDER
        )
    end
end

Line 1: starts the for loop with the variable woRec to store each record in the WO-TASK subtable.

Line 2: creates a variable where we find any WR-TASK records that have the same TASK-POS data as the current record in the loop (woRec).

Line 3: starts the if statement checking if the variable from line 2 (wrCheck) is equal to 0 and if it is

Line 4: then we create a new record in WR-TASK

Line 5: then we link the newly created WR-TASK record to WORKORDER using the link from woRec. If you need to copy other data then add a semi-colon (;) at the end of line 5, then add each new field you need to copy. Keeping everything within the close parenthesis ")".

Lines 6 - 8 close their respective commands.

I haven't tried it out, but it should work as you wanted.