I don't know if this can help you:
The Birthday Cake method I used is very similar to this one:
Worked like a charm. But had to restart once when Jordan Cross aborted walking down - it tends to happen if anything interrupted the sequence leading to Jordan coming down for the birthday cake. In my case I was "slightly spotted" (Someone got a "?" while I was making my way back to hiding while putting the cake topper on once).
On the restart I did it clean and everything happened as expected.
I did it by killing Ken Morgan first by poisoning the food he tastes, going into the Kitchen, grabbing the Cake Topper and doing the rest pretty much as in the video from @TrueBlueMC .
Good luck! You're a better player than me! Should be a walk in the park for you.
I also made these notes after I finished pulling it off: