Confused !! Citizenship help please

 Good Afternoon,
Can someone please help me with my situation.  It's a little confusing but I hope i can explain to the best of my abilities.
Thankyou in advance for taking the time to read and help.   So,  my father became a UK citizen in 1973 and was given a passport & a registration certificate.  My siblings were born abroad in 1971 & 1972 and were also given citizenship ( UK passports & registration certificates ) along with my Mother.  I however was born abroad in 1976 and was only given a UK Passport & NOT registration certificate so I am now considered a citizen by descent and my siblings are considered otherwise by descent, since I was born after my father had became a UK Citizen.                                                                                                   So,  my question is that is it possible that I can somehow obtain a registration certificate ?  Can I do like an OATH taking or fill out some Paperwork that can help me obtain this ?  Or is this totally impossible to do or obtain ?       Thank you very much again for all the help.

Have you spent any time living in England?

Hello , yes i lived in the U.k and went to school from 1978 to 1990 then moved to the U.S   ..

I misread this the first time and thought that you were after changing your status in order to pass on your citizenship. I don't think that you will be able to swear an oath or do some paperwork to change your status, however, as you have spent more than three years in England you may very well be able to pass your citizenship along to your children with form MN1. The only real difference between citizens by decent and the regular citizen is the ability to pass on your citizenship.

Have a look at the guide here: http://www.ukba.homeoffice.gov.uk/sitecontent/applicationforms/nationality/guide_mn1.pdf

Specifically "Children born abroad to British parents - Section 3 (2) or 8
section 3 (5) application."