Aargh! I feel like I've been frying my head scouring the internet for parental control apps but can't seem to find anything that is practical for my circumstances:
Our 2 DSs share an android tablet (version 4.4.2 which doesn't appear to be able to register multiple users - ggrrrr!) and an old windows laptop to play / view online content or games that are loaded onto the laptop. The internet connection / router is from PlusNet.
The main aim is to find some way of monitoring and limiting each DS's screen time to an agreed level.