Form UKM - Mother's Name Change Documentation

[Bobomo]

I was born in 1981 to a British mother (by birth) and American father in the United States. Due to divorce, my mother did not register me as a British citizen prior to my 18th birthday. As I understand it, I should be able to fill out form UKM to "register" as a British citizen.

My question has to do with this instruction from the guidance document: "If due to marriage, your name differs from that of your mother, as stated on one or both of your birth certificates; you must send marriage certificates that evidence that yours and/or your mother’s name has changed."

I have my father's surname, and my mother now has her given name, being unmarried. I can obtain a marriage license to document the marriage, but the complication arises that my mother had retained the surname from her prior marriage up until marrying my father, so the license may show that name and NOT her given name. It is unlikely I can retrieve a marriage license from that previous marriage given the elapsed time, status of the husband, and my lack of legal standing in that relationship.

I was wondering if you had any advice on what may be sufficient to document surname status between my mother and I. My thanks for reading.

[Bobomo]

I was able to get a copy of the marriage license, and it does include my mother's given name (in addition to full names of her parents, both British) as well as the prior name she was still using from a previous marriage. Now: she has an expired British passport in the name from the previous marriage that I was planning to submit for "Her expired citizen of the United Kingdom and Colonies passport". Will the marriage license and my birth certificate stating all the various names be enough to connect the dots and correctly identify my mother for the purposes of form UKM?

[Bobomo]

I apologize but I cannot seem to find a way to edit or delete this thread. I should have identified all of my documentation before posting in order to present a more succinct question, which is: my birth certificate, and my mother's birth certificate both clearly identify her as my mother - names are the same. However, the expired British passport that is also required of my mother is in one of her married names (not my name). Should I include any documentation to link the name on that passport back to her given name? All other identifying information in the passport (DOB, place of birth) match, it just does not include any reference to maiden name.