Ariana vocal-produced this little number ... (Image via #RentSingAlong)

Frankie Grande and his sister Ariana Grande (ever heard of her?) ganged up for a duet on “Seasons of Love” from Rent as part of the Rent Sing-A-Long initiative to celebrate FOX's upcoming live version of Rent ...

FOX airs its live Rent on Sunday, January 27, 2019 (8 p.m.-11 p.m. ET/PT tape-delayed).