You can just pick the path of romancing Gastors. Included Papyrus, Sans, probably Wing Ding too(nah i'm flirting with everyone and keep the necessary things and got the harem route twice(chain, paper, some stuff other). The last one it took more than 3 hours if you don't skip from the very first you fell). But really, I flirt with everyone like Flowey/Asriel, Grillby, the bunny lady in the Snowdin, Sans, Papyrus, literally anything possibly to get the choice to flirt with. Wheheheh, i got trio Gastors as datemate. The extra part is so much great for me, also it got me laugh at some parts. Now i'm looking forward for the Mafiafell's progress🙂