One other bypass I have been using (suggestions of improvements are welcome): to emulate a real sitout (if you and your players prefer this to human substitutes) create dummy1 and dummy2 (or similar) and use two phones to register them as a pair; if the number of pairs registered is odd with just a few minutes to go then unregister the dummies and quickly edit the tournament to allow the current even number of pairs, if not then keep the phones underhand to affirm that you are still there as often as required.