Unbelievable the hassle and intrusion that all the scumbag liars and overstayers in recent years have caused for ordinary decent Filipinos wanting a holiday here.
Personally I'd be inclined to send the in-laws some airtickets to the Phils, invest your time and money in your business and lives there, and stick two fingers up at the UKBA until you decide to put your affairs in order to be able to apply for a settlement visa sometime in the future.
Thank goodness the Phils BI haven't adopted 'reciprocal arrangements' !