In ground vinyl pool with liner problems.?

No easy solution. Must solve the problem of settlement first or your just throwing good money away. First order would be skimmer repair, that leak will surely undermine on a daily basis. Must cut "deck" away from skimmer to prevent further slippage. The gap occurring at pool edge could be filled with "quarry blend" gravel/dust. This will fill all little cavities and tighten up real well after a few rains. You can add more as more settlement occurs......temporary plan of course.