Randomizing pairs of statements that are also randomized

I need to randomize pairs of items that are themselves randomized in one question. In essence, it's nested randomization. There are also a couple of items that are not paired that need to be randomized in the list, too.

I've tried using multiple constructed lists, but the final randomization statement randomizes all items and does not keep them in pairs. All items come from the same parent list.

For example, I start with one constructed list where I'm randomizing the pairs (named Q3abRowList):

ADD (Q3RowList,1,2)
RANDOMIZE ()

After creating several of these constructed lists I build a "final" constructed list to randomize them:

ADD (Q3abRowList)
ADD (Q3cdRowList)
ADD (Q3RowList,5,20)
RANDOMIZE ()

It is this last randomization statement that overrides the randomization of the pairs.

Thoughts on how to accomplish this?