Manu Samoa had been due to play in the last two legs in Spain in January, but had to withdraw late due to Covid-19.
The first squad back in the series features nine debutants.
Samoa are in Pool B with Australia, England and Spain.
Meanwhile, the return of Jerry Tuwai at the Singapore Sevens is a boost for Fiji.
Head Coach Ben Gollings was also eager to test out some of the young guns like Filipo Bukayaro.
Fiji are paired with Ireland, France and Japan in their pool.