I can understand why DPP wouldn’t want to merge, but why are SDP and CDP still individual parties?
SDP base these days are in the South and fairly rural. So SDP-CDP might not be that different in terms of ideology the SDP view that CDP is too urban bases would be a problem plus SDP being the successor party of SPJ gives it a historical legacy that it might not want to throw away.
Anyway these merger talks
https://uselectionatlas.org/FORUM/index.php?action=post;quote=7096005;topic=298240.650;num_replies=651;sesc=ab9e995c3a96f7e2d1998839d333afd6always tend to take place toward the end of he year. The reason is after New Years the government subsidies for political parties are doled out based on the number of MPs a party has on Jan 1st. So the thinking is "if we all merge we can get a very large bloc of money !!!" followed by "wait, we actually do not agree on policy and even if we do not merge we will still get the same amount of money but just spread out over several parties" Of course there is an argument of economy of scale argument that organizational cost overhead of a party is such so that if all like minded parties unite the combined money can be spent more efficiently.