Active FOX crossovers

I talk about shows what are currently airing on FOX but first I have couple OT questions:
- Are there a rule that sitcom/ comedy cannot crossover with action/ drama?
- Also can an active TV show can do a crossover with ended TV show, like one of the characters of ended show appear in active show?

To the topic.

I exclude FOX animated shows because most of them are already connected (The Simpsons + Family Guy + Futurama + The Cleveland Show + American Dad) and ask what shows could do a crossovers (read my signature and you realise why ask that) and I exclude Bones and Sleepy Hollow, because they are connected too.

Brooklyn Nine-Nine and New Girl just did a crossover, altogh B99 had more screentime in New Girl than New Girl in B99.

In my opinion it is hard to FOX shows to do crossovers.
- Gotham: DC property without real-life version of Gotham
- The Last Man on Earth: post-apocalyptic show
- New Girl could do a crossover with Lethal Weapon as they both are set to Los Angeles. Also New Girl could do a one-way crossover with The Grandfathered.
- Pitch: set into San Diego

Whay you think? What other FOX shows could do a crossover with each other?

I am a fan of TV crossovers. It connects different shows and puts them into same universe