When applying for a UK visa as a dependent, do you need to add marriage pictures and other documents aside from the marriage certificate?

It is always a good idea to add pre marriage and post marriage photographs and other documents such as wedding receipts etc as support of the application basis as it demonstrates that the relationship is subsisting and durable. It will also add more weight onto the application. 

You may wish to consider contacting My Legal Services who are experts in this field of UK Immigration visas.