The Southern Football League has published the following statement this morning (10/04/18):
The League Secretary sought permission from the FA to extend the season by a maximum of seven days. On Monday afternoon that permission was granted, but only in certain circumstances.
Matches can only be played after 28th April whereby a Club has fully allocated its Saturday and two midweek dates. Furthermore matches taking place after 28th April must not involve any Club that is competing for promotion, including play-off positions, or relegation.
It may be possible that the League will be required to rearrange existing fixtures in the best interests of the Competition to facilitate the aforementioned.
The full statement is on the league website here.