Tin Soldier, is it doable? Council tax, household bills, gas, electricity, broadband, water plus other utilities, not to mention other things like food shops, insurances and transport to work.
If it is shared ownership I can understand you saying it is doable, because then on their low wages they could get help for the rent part via UC. I am pleased people on low income can get on the property ladder but the younger Grandchild has done nothing fantastic to get all this adulation, in fact she works part time, lived rent free, paid out for nothing, no wonder she could save.
See the difference between the older one who paid her way done the cooking, and worked with two very painful conditions. She has you and her princess younger sister sussed OP.
If this is true I find your younger Grandchild lazy and greedy, and you horrible for not recognising the one who does not take.
I truly hope this is made up, because I was that older sister. The difference being I stuck two fingers up to then and succeeded. I hope the oldest sister does just that and Grey rocks you. You don't deserve your lovely elder Grandaughter, like I did not deserve my toxic lot.