DPP, SDP and RP have all expressed interest like SF for the reason that it was uncontested last time, so declaring such an interest wouldn't look that bad. But at the end of the day, only 1 or at most 2 of the parties will go ahead. The parties (except WP) are all about equal in strength, so by the time they hammer out all the turf splitting, SDP and RP will have to pull out of TP since they have their own last-contested GRCs.
The problem is that, overall, all the opposition parties will each be confined to one, two GRCs, which doesn't help in the expansion plan of any of them even if all of them wins something. This was a problem identified by those who support WP's self-sustaining model but still a problematic argument for those critical of WP who advocate a pan-opposition form of unity.