Complex sentence: Between 1807 and 1815 she had managed to make the acquaintance of some members of the Royal family, and from this time onwards seems to have been obsessed with the idea of raising herself, at all costs, to their social level.
Split into simpler sentences: Between 1807 and 1815 she had made the acquaintance of some members of the Royal family. From from this time onwards, she is claimed to have been obsessed with the idea of "raising" herself, at all costs, to their social level.