Cain and Chas in ED. Half- siblings and also cousins (the mother had an affair with her brother in law)
Cain and Charity: distant cousins and on/off lovers ( making their daughter a relative of everyone in the family twice over, I think

)
Jacob, Leyla and Alicia in ED -Jacob was raised by one sister (Alicia) but the other, Leyla, was his birth mum. Leyla was also engaged to Alicia's ex David a few years ago.
Ross and Debbie: employee and boss, as well as lovers and potentially in laws.
Cain and Debbie: work colleagues and father/daughter
Rachel and Jai: employee and boss, parents of Archie. The current Sharmas are all business colleagues as well as family.