Mbeumo and Wissa are highly sought after by other Premier League teams, and as their contracts are due to expire in a year, Frank has admitted that the club might be open to selling them if a suitable offer is made.
The Bees have an option to extend their contracts by a further 12 months, which gives them some leverage in negotiations.
Frank has stated that Brentford is a club that sells players, but he would like to keep Mbeumo and Wissa if possible.