I found the following information in the Indiana WPA indexes (spellings are just as I found them):
Joseph Henry Lensing married Jeanette Orr on 8 Jun 1905 in Vigo County (book 19, page 111).His birthdate is listed as 2 Feb 1880.Her birthdate is listed as 11 Jul 1884.
D.H. Leusing (female) born to J. Leusing and J. Orr on 19 Jul 1906 in Vigo County (book H-10, page 14).
Robert Leusing (male) born to Joseph Leusing and Jenette Orr on 5 Sep 1910 in Vigo County (book CH-26, page 59).
I know that this doesn't answer your question, but it gives you some information to work with.
Since Joseph didn't marry until 1905, he should be with his birth family in the 1900 Vigo County census (I have a copy of the census, but it is not indexed, otherwise I would look it up for you).If you can find them, you should get the information you are looking for.
Also, it is very likely that Leusing is a married name for Margaret and Ella.There is a Vigo County WPA marriage record for John A. Leusing and Margaret Quinn on 28 May 1918 (book 48, page 77).His birthdate is listed as 14 Dec 1882, the right age to be a brother to Joseph.Her birthdate is listed as 7 Nov 1884, which matches the SSDI entry you mentioned.I can't find anything on Ella, but the situation is probably the same.