Have you contacted the Cemetery to confirm your William and Ella are buried at Sunset Memorial Park ? Or to see if any other family members are buried in the same plot perhaps ?
Perhaps this entry has the names of the people you are enquiring about.

Which would make Ellen T born about 1908 and Julia born about 1904 (which is correct for the SSDI record - posted earlier.
Bensalem, Bucks, Pennsylvania
William Mcclelland 50 Born Ireland. Farmer.
Ellie M Mcclelland 51 Born PA
Julia E Mcclelland 16 Born PA
Ellen T Mcclelland 12 Born PA
Margaret Mcclelland 11 Born PA
Thomas Nolan 45 Hired Man
William Lankins 65 Hired Man.
Sandra