I have no more knowledge of this than anyone else here, but IMHO the surname alone makes it unlikely that this child descends from the Romanovs. Possibly the child was an offshoot of the Sheremetevs? They were a very large, old and wealthy noble family after all, and it would be easy enough for "grandpa was a Russian Count" to become "grandpa was a Russian Grand Duke", and then claim the highest GD possible? Especially when people had only the vaguest of notions of how the Russian nobility system worked, Europe was crawling with Russian noble refugees and there was no internet for people to try to check up on such things?