RootsChat.Com

I have reached one of those places in my research where I have the option of trying to convince an LDS bishop that I am indeed descended from so-and-so, so that I may have the privilege of going to Salt Lake City and viewing some records that are not accessible in any other way.  Perhaps some of you have had the same experience. 
I have no idea what would be in this kind of record, if I were to go there.  The website doesn't really tell me very much at all.
I would want to know that it was going to give me something I wanted to know before I even considered going.  The record in question is of a woman born in 1794 in the Netherlands, my ggggmother.
I'm also wondering what other sorts of things one might find there that couldn't be found in any large city.  I live in Canada, but, to be honest, I'd rather take a trip to England than to the US!  Unfortunately, you can't send anyone to do "look-ups" with this kind of a restricted-access record.
Please share your experiences!

thanks,
Loo

I could really use some good advice as to which direction I should go in next on this one:

I am trying to find birth information for Eliza STEWART and her sister Anne/Annie STEWART.

In every census, starting 1861, they are listed as having been born approx 1841 and 1840 respectively.  Eliza is said to have been born in Marylebone, and Annie in either Plaistow or Chigwell (depending on which census one consults).  Plaistow appears to be in West Ham registration district, and Chigwell appears to be in Epping registration district; they are only about 10-15 miles apart. 

I have what I am fairly certain is the correct marriage certificate for Eliza STEWART to John WEST, 20 Feb. 1864.  I am confident of this because her address at marriage and occupation corresponds to census information;  the census data are the relevant ones because the information about their son is correct, including his occupation.  The address is consistent through many censuses.  On this marriage certificate, Eliza’s father is said to be one Henry STEWART, a painter.

Annie never married, and continued to live with Eliza through the 1901 census.

There is only one Eliza STEWART, born Marylebone during this time period, so I thought this would be really easy!  I ordered the certificate, but it was a waste as the parentage is completely different – if memory serves, it was William STEWART, and he had a totally different occupation;  the mother was Dorothy MOSSMAN.  Also, the address is an area of Marylebone, the west side of it, where no one else in my large family tree ever seems to have trod, although there is a great deal of crisscrossing elsewhere.

I found only one relevant Anne STEWART, born Epping, in this time period.  I thought, once again, that this would be easy.  But she appears to have yet another set of parents, the father being Hy Benjamin STEWART, according to IGI.

It seems that the more I dig, the worse it gets!  Nothing seems to match.

What do you think I should do next?

Thanks.

Am looking for:

1851:
Henry (and ?wife) STEWART, daughters Eliza (approx 9 yrs, born Marylebone?) and Anne/Annie (approx 10 yrs, probably born somewhere in Essex - Plaistow or Chigwell?).  Henry is a painter.  Wife may have been deceased by then. 

1861 and 1871:
Henry STEWART, painter.  Wife unknown. They would likely have been born prior to 1820, but I don't know where.  Living in Marylebone, but could be deceased. 

No need to check 1841, as they were not living in London at that time.

Thanks enormously to anyone who is able to check on this for me.