You're seeking to evict your brother-in-law, a permissive occupant in your late husband's former property, to sell your house. Legal advice suggests you can indeed file an eviction suit after issuing a legal notice. While selling with a pending suit is possible, it may lead to a lower sale price as buyers might take on the eviction themselves. It's generally advisable to resolve the eviction before selling, though a sale agreement conditional on the case's outcome is also an option.