Ann is roughly 40 when she dies of cancer. Her daughter Beth is 17 at this time, and turns 18 about two weeks after Ann dies. Ann has always been unmarried. (Beth's father is not relevant at all to the plot other than the fact that he just isn't in the picture.)
Ann has two living relatives beside Beth: her own mother (Carol) and an uncle (David, Carol's younger brother).
She has been estranged from both of them since Beth's birth. Carol disapproves of her life choices, and Ann dislikes visiting/hosting her, but Ann cannot financially afford to cut all ties with her. Because of this, Carol has seen Ann and Beth roughly three weeks/year for the past 18 years. Carol has financially contributed to Ann's household, but all support came with conditions and doing anything Carol disproved of would result in lesser future support. David, Ann's uncle, has not been in contact beyond holiday cards in nearly 18 years due to threats from Carol, who is blackmailing him. Ann is aware this is the reason for David's silence, and while she's upset/disappointed about it, understands why her uncle hasn't been in touch.
While dying, Ann realizes that she does not want Carol to receive custody of Beth. She calls David, who agrees to take custody of Beth. Ann updates her will to reflect this without telling Beth or Carol. She does tell Beth that David will help her. Ann dies when Beth is just barely under 18. David arrives, ready to uphold his promise to Ann. Carol is angry, as she had assumed she would take charge of Beth. Beth is more than willing to go with David instead.
I can't find the answers to the following questions.
1. Would Social Services etc even get involved? There are two blood relatives ready and willing to step in and care for Beth, and frankly, if it came down to a court case and/or legal wrangling, Beth would be 18 and a legal adult before anything would be finalized.
2. Can Carol contest it or block Beth going to David? Courts tend to give first preference in custody issues to grandparents, so it would seem that Carol has a strong case (grandmother she knows vs great-uncle she's never met, Ann's will was updated while she was under influence of painkillers/chemo, Beth is being swayed by David's wealth, etc.). Carol's argument basically boils down to the fact that she considers David unfit since he's homosexual, and she views it as her moral duty to keep Beth away from his influence.
3. If David was super-prepared (and if Ann approved and helped him with whatever permissions necessary), could David basically show up with all the legal stuff handled/filled out, get Beth's approval, and get her in front of a judge and adopted swiftly? If so - or if not - what time frame am I looking at for best/worst scenarios?
4. At what point will legal entities throw up their hands and say, "You know what, she's 18, this is a pointless custody issue"?
David and Carol are both fairly wealthy, though David is richer. Beth greatly dislikes her grandmother and is willing to go with her great-uncle if only to spite her grandmother, but her mother's recommendation of David makes her trust him. Both David and Carol are able/willing to care for Beth. David will offer legal guardianship to Beth, but ideally he would like to formally adopt her (as a minor, if the courts can move fast enough, or as an adult if they can't) if she is amenable to the idea.
What complications am I missing? Or since she's so close to 18, there's a will with her mother's preference, and since she has a clearly stated preference herself, is this all just overthinking the process?
Search terms: "adoption after death of parent", "adoption by relative after parental death", "adoption time frame", "adult adoption" (mostly in terms of estate planning, it seems), "teenage adoption", "adoption dispute", "requested legal guardian after parent death", "adopting legal ward", "uncle adopts niece/nephew", and several other related search terms. Most results seem skewed towards what will occur after adoption rather than the adoptive process itself, so even if someone could correct my search terms, I'd be grateful.