Hi @outlander
I'm sorry you are going through all of this - and really - you are at an age now where it is perfectly normal to want your own front door - or at least be in charge of that front door.
You said it all when you said "You have no control" - and your family has lived off your good nature for as long as I have known you which is several years now. Your sisters are growing up and starting on their own lives - or planning it - and worst of all - ah - ah - ah -
Your pop's daughter moved in and is free-loading - it will be tough for you to deal with her I am sure - but she either needs to man up or get out - and neither will be easier for you.
Also - I am first born too so I got the load on the eldest child's shoulders from an early age - and whatever my younger siblings did I got the blame for it - and now - they are no part of my life - so - yeah
Independence has a price - and you are concerned about this price - especially when it comes to your Pop - he's frail-aged now and scared of being in residential care - something I really understand - that's not for me either - so - whereas none of us can tell you what to do we can voice our ideas.
You need time off from your pop - people do get respite leave at times and his daughter is right there - to pick up some slack - and your sisters seem pretty independent.
Your moving out of the house doesn't mean you give up full-care of pop - you can still have a share - but that share needs to be taken on by someone else - not you all the time
You have come such a long way in the time I have known you - it's time for you to take the next step - just what that step is - only you know.
Other people here have written some really good info - we are for you - we get it.
Sending some really gentle virtual hugs
Owlunar