Hi Kinguni !
I understand your feelings about the pool and that you really want to keep it as an ingroundpool.
I hope I don't come through ignorant to you problems, but have you considerd to build up new poolwalls by yourself with materials from your local store of building materials?
To simplifie the building process i would converte the pool to a one water level pool. And shrink it in size to be able to build it the way I have planned. approx 600mm around the pool.
This is how i would have done it:
1. Drain the pool and put on braces to stabilize the walls so they won't fall in.
2. Cut up the bottom of the liner and start to even out the bottom of the pool so you get the depth that you want. The soil underneath is already compact from the many years underneath the pool. So all you have to do when you move the soil from one end to the other is to pack it with your feet, layer by layer. Depending how high your groundwater is drain the poolbottom with draining hoses.
3. decide how big pool you want and put on celluar plastic on that area. of course do you want to get the pool as big as possible so you have to calculate with how thick bricks you will use for your walls and then add 400mm plus the thickness of the bricks there you have the meassurment for the pool.
4. Reinforce the whole area with rebar-carpets(6mm thread) and also 400mm outside the celluar plastic where the walls will be placed.. Under the rebarcarpet where the wall should be placed mount 2 single rebars(12mm) 50mm from the bottom on distances.
5. Pour concrete on the whole area so you get 100mm all over except where the walls should be where it will be 200mm beacuse the lack of plastic in that place.
6. after that use bricks that are made from light clinker material and brick up the walls so it's height ends around 70mm(thickness of the new pooldeck??!!) over the existing concrete deck.
7. when you have bricked up the walls will you have a space between the old plastic walls and the new brickwall, about 400mm. in that space do you place all the plumbing before you fill the space with a macadam or something similiar to the level it with the existing pooldeck.
8. When you pour the new deck you will pour it to the new poolwall so it evens out. If you not have been accurate with your bricking just level it by molding on the top of the last shift. That is also preferable to do beacuse it stabilize the whole construction.
9. order a liner in the right meassurments and then you have a new pool that will last a lifetime.
This is very basicly how to do it. What I have left out is reinforcements on poolwalls longer than 6m and reinforcements that you have to add on every second shift of the brickwall and how to seal the light clinker both on the inside and the outside and stuff like that.
If you are interested I could search for pictures showing the process and I could also describe every step in the process more accurate.
This is a very doable DIY project that won't cost to much money and not to much work either.
Inpool steps is an easy thing to add if you want. But that would add extra cost on the liner. It might even be possible to use the poolstairs you already have with some additional welding of the liner, but that I'm not sure about.
//Mats