My mother had Alzheimer's and it was beginning to be obvious that she would not be with us for long. I asked a priest friend of mine who said that he felt uncomfortable in performing a chrismation on her as she had not made that decision when she was fully able to several years before. My wife and I were worried, she had not been to church in several years due to various circumstances. When I called the Episcopal Priest at the church in my home of origin where she had been a member of for over 25 years, he said he would bury her but as no one could remember her (this was sad she taught in the parish school for years) he would have to ask for $2500 as a donation for burying a non-parishioner.
As the days progressed, I noticed that my mother was crossing herself in the Eastern Orthodox way, kissing the family icons and even having my grandson, then 2 bring her the icon of the Theotokos from the family room to her room. She would talk to the holy mother, pour out her heart to her and kiss the icon.Upon seeing this I went to another priest I knew and told him of my mother's problem and he stated, "Of course I will Chrismate her, God has made her like a child and as I would do for a child I will bring her into the Church". He chrismated her and during the service, we witnessed a miracle, she became alert and oriented, she answered all the questions of the priest during the service, recited the creed, and it was very apparent she was making her own decisions. After the service she was her old self for three hours. After three hours she stated she was tired and went to bed, when she awoke she was back to her previous Alzheimer's state. Father told us we had been given a miracle to let us know that she really did want to be orthodox. She communed three times prior to her death and always looked forward to Father's visits bringing her the body and blood of her Savior.
One can not dismiss the value of any conversion, even that of a death bed conversion I have learned.