Hi,
If your question is more about how, then this discussion would help => Update ASCENDAS-HTRUST to ASCOTT TRUST
If your question is more about why => short answer: because it is currently not supported 
Long answer: Technically, it is possible but since my upstream does not directly provide such data. It can be quite tedious work. 1) Build the system to handle it properly including providing overrides if some users disagree with the way StocksCafe decides to handle it and 2) manually track all such merger and acquisition and input them into the system.
However, to be honest, this is something StocksCafe have to tackle sooner or later. Maybe we can start with the upcoming CCT and CMT merger => Any feature to cater for upcoming potential CCT and CMT merger?
Cheers,
Evan