David Denton is to leave Worcester, who sign fellow Scotland international Cornell Du Preez and Wales centre Ashley Beck.
Duncan Weir, Scotland team-mates Cornell du Preez and Sam Hidalgo-Clyne and Welshman Jason Tovey will leave Edinburgh this summer.
Worcester Warriors sign Scotland international loosehead prop Ryan Grant from Pro12 side Glasgow.
Worcester Warriors' New Zealand-born centre Jackson Willison is to leave to join Bath at the end of the season.
Leicester Tigers sign Worcester Warriors and Scotland back row forward David Denton for the 2018-19 season.