Re: When Can You Claim Adverse Possession of the House You Live In
Since the grandparents were unable to continue to grant permission post-mortem, that permission would have to come from whoever would have inherited the home. Have you discussed this with any of your relatives? Have they given you permission as far as their possible authority to do so goes?
You said there are no designated heirs (no will). Maybe this is more properly a probate matter. Although it definitely has aspects of Adverse Possession (adverse against other potential heirs), determining the disposition of the real and personal property of those who die without a will is a different area of law (that I am unfamiliar with). If I were in this situation, I would start by getting advice from an attorney that handles probate cases.
I'm a surveyor, not your surveyor & not an attorney.
Advice is general survey, not legal. Hire a local professional for specific advice.