To qualify for a Dependant Visa, you must be a dependant family member of a qualifying migrant. The Immigration Rules define a ‘dependant’ as being a:
It is highly unlikely that any other family members would be successful in claiming dependant status for the purposes of a Dependant Visa. To obtain a Dependant Visa as a spouse or partner, you must be the spouse or partner of someone who is applying for a visa at the same time as you are making your application for a Dependant Visa
An essential requirement of the Dependant Visa is that the families have enough money to support themselves without having to rely on public funds.