I'll just leave it at, it's common for some developers to introduce characters from their other games into the projects they're currently working on. In this case, Trisha from
SL appearing in DmD. It's not the first time Mr Dots has done this.
If you've ever played
Melody, one of his other VNs, you'd have noticed Georgina was in the dinner scene with the MC and Amy went they went on a dinner date together, even though she had no dialog at all in that VN. Sophia and Xianne were married in Sunshine Bay in one of the previous updates in SL as well, who were also in Melody.
It's due to the location F & D are currently at, which is currently in Sunshine Bay. So it would make sense to see some of his characters from other games into this one.