Calum Chambers is ready to go on loan for a season to recapture his form that earned him three appearances with England in 2014.
Watford safety secured their Premier League status last season, but it wasn't enough to keep Flores employed.
Sinclair had been keen to leave Anfield in search of greater first-team opportunities.
Walter Mazzarri has been appointed the new head coach at Watford.
Spaniard guided Watford to FA Cup semi-final and 13th in the Premier League.
Jurgen Klopp is expected to ring in changes after Thursday's Europa League win.
Signing forward pair would set Leicester back by at least £40m, according to reports.
Liverpool host Watford in the Premier League on 8 May. Find out where to follow the game in the UK.
Watford beat Liverpool 3-0 at Vicarage Road earlier in December.
The Magpies won a dramatic game at St James' Park thanks to Andros Townsend's goal.
Connor Wickham's goal sends Palace into just their second domestic cup final.
Flores is not planning talks with owner Gino Pozzo after FA Cup semi-final defeat.
Wickham sends Palace into just their second ever domestic cup final and first since 1990.
Crystal Palace face Watford in the FA Cup semi-final clash on Sunday. Find out how to follow the match in the UK.
The 19-year-old, at the centre of a dispute over his future, scores against Leicester Under-21s.
The Hornets suffered their fourth consecutive defeat in the Premier League.
The Gunners closed the gap to leaders Leicester City to eight points.
Alexis Sanchez, Alex Iwobi, Hector Bellerin and Theo Walcott all net for the Gunners during emphatic home win.
Arsenal host Watford in the Premier League on April 2 (Saturday), Find out where to follow the game in the UK.
Flores said that he is very happy at Watford amid ongoing speculations linking him with a move back to Valencia.
The Colombian says that national team doctors will assess the issue.
The 33-year-old is yet to play since the FA Cup victory over Burnley on 30 January.