Switch and else if logic question

Hey Everybody,

I am trying to add a custom column using the custom column formula as follows:

SWITCH (
    TRUE (),
    [FF]="D" and [PB]="A", "First",
    [FF]="De" and [PB]="A", "Second"
)

Power BI is telling me the name SWITCH wasn't recognized.

I have posted the .pbix file here

Pls advise formula to check multiple conditions in numerous columns and return distinct values.

I am also very open to a derivation on the following "IF" formula:

(if

([FF]= "D"

and

[PB]= "A")
then"First"
else"Not First")

BUT, that allows me to tag the "this and that" conditions, seperated by multiple "or" as I go down the stack of all the conditions I have to check for.  the "else" line of code above is what is throwing me.

Thanks so much!!!

mibu