verifying lena rian or ryan's birthdate

Hi it is unknown to my aunt and uncles that lena spelt her name RIAN OR RYAN. They knew that in norway they used the I for the Y. Her birthdate is march 18, 1863. I 've been told she may have spelt her name Rian and then when she arrived to the states they ( immigration board spelt it ryan.) I have been told she came from either Bergen or T rodheim. Her death certificate lists her last name as Lena Ryan Olson. A marriage certificate that I've located said Oline Ryan and Morris Oleson in 1881. Both found in Minneasota. Now in Nord Trodenlag we found a matching birthdate with the matching last name "Ryan" (Ryanpladds). Which I thought would be her. I also was told that when she left Norway she left with a younger brother. I was wondering if some one could help me verify her birthdate once and for all or direct me in the right direction on where to start. Thanks KIM