So far there have already been three or four matches where the teams have rune out of time before completing the minimum 12 sets. Although the rules say that a minimum of 12 sets must be completed they do not actually say what must be done if that fails to happen. As a committe we have decided that until it can be clarified at an AGM the best thing to do would be to treat it as a weather interruption and use rule 11 to sort it out without, of course, there being any time remaining to keep, merely an obligation to complete the 12 sets.
A version of rule 11.1 that you might use would therefore be
11 If 12 sets cannot be completed because of weather or lack of time then
11.1.1 If the cause is not lack of time then the remaining time should be noted
11.1.2 There will be 2 weeks for captains to rearrange a match. The home captain shall offer three non-conflicting dates, two of which shall be weeknights (unless the home team play at the week end, in which case two of the offered dates must be at the weekend), for the completion of the match. Failure to do so will result in a points deduction to the home side. A rearrangement has to be agreed within 14 days but the date of the replay can be any time before the September deadline.
11.1.3 Two players may be replaced by substitutes.
11.1.4 If both captains agree to restart the match as a new match the teams are not restricted in the number of substitutes.
11.1.5 The Match Secretary shall be informed of the replay date. If no agreement on a replay date has been agreed within 14 days of the original fixture the match secretary shall be informed.
11.1.6 Unless there is an agreement to restart the match as a new match, all that is required from the replay is that the minimum sets be played to reach a total of 12 or that the remaining time be played out (but a minimum of 12 sets must be played).