Don Lothario

bev6usa​ Don lives in the Caliente family at Sultry Springside in Oasis Springs, alongside Katrina, Nina and Dina.

I looked for them in Osis Springs, but I couldn't find them. My sim hasn't met him yet

If the family doesn't live at Sultry Springside any longer and you can't find them among the sims in 'Not in world' you could start a new game, upload the family to your library and put them into your save so that your simcould meet Don.