Schengen Visa (dependent): No Marriage Certificate

Please help me with this query:

Myself, My spouse & our son are planning to do a Euro Trip. We are presently in London on a Tier 2 visa, holding an Indian Passport.
I was made aware that, a marriage certificate is a must have document to obtain a schengen dependent visa.

We do not have a marriage certificate, however, my spouse & kid's passport(s) have my name endorsed on them in the husband & father sections, will this be considered in place of a marriage certificate to issue a visa?

Are there any alternatives?

Thanks in advance, your suggestions will help us.