The invention relates to a connector element for use in a flashing assembly for roof windows mounted side-by-side comprising at least two flashing members. The exterior side of the connector element having an exterior side intended for facing the exterior in the mounted state comprises a gutter with two longitudinal edges each being adapted for engagement with an engagement section of a flashing member. At least two flanges projecting from the interior side, which is intended for facing the roof in the mounted state, and in parallel with the longitudinal edges of the gutter are adapted for coming into engagement with a mounting bracket arrangement including at least two mounting brackets associated with two different roof windows and adapted for a locking engagement with the mounting bracket arrangement thereby fixating the connector element in relation to the mounting bracket arrangement in at least one direction. Each of the at least two flanges are intended for coming into abutment with a surface of one of the two mounting brackets and each flange is provided with two or more curved recesses, each recess being adapted for riding on intermediate members of the mounting bracket arrangement. The invention also relates to method for mounting a flashing assembly.