Martin (1992: 137-8):
Similarly, the nominal groups realising Circumstances of Extent, or filling Pre-Deictic, Pre-Numerative, Pre-Epithet or Pre-Classifier positions may be taken up as participants in a discourse, although the textual motivation for selecting a nominal group realisation may not have been to introduce a new participant in the first place. This is illustrated with respect to Pre-Numeratives in [3:75].
[3:75] I got two jars of mulberry jam.
— Let's see them / I hate it.
Here again Martin violates his own model in its own terms by proposing a reference chain between a non-participant (pre-Numerative: two jars) and a participant (them).
To be clear, in SFL theory, the reference item them makes anaphoric personal co-reference to the referent two jars of mulberry jam (just as the reference item it makes anaphoric personal co-reference to the referent mulberry jam).