Registration 574735 (1910) is for an oval bowl and 578132 (1911) is for a circular bowl of the same design. There is no sign that any other pieces were produced under these patterns in the registration documents, but I have found a sugar and creamer that almost certainly belong to the same set. They have no registration number but display the same pattern of segmented lower body, a ring of diamond shapes, and a shell pattern on top. I would say it's a little unusual for other pieces in a set not to be marked with the registration number.
I would speculate this is the penultimate registered tableware set for Molineaux Webb. Registrations 609921-2 in 1912 are also a double of a pattern on an oval and circular bowl. I have yet to see other examples from those registrations but it wouldn't be a surprise if some turned up.