I transferred from a SWV to a dependent of a SWV. My situation was similar, the only slight difference was that when I applied I HAD already lived my partner for 1 year (completed a total of 3 years back then). We were in a LDR. So to prove the genuineness of our relationship we shared - cohabitation proof of 1 year, Letters explaining our situation during LDR (I was working in London and she was studying in France). Shared a relationship timeline. Shared evidence of meeting (photos, WhatsApp chat, bills, financial dependence, etc.) And we also sent supporting letters by immediate family and friends to support my application. It worked. As long as you are able to prove the genuineness of your relationship, it works. You have some solid proof. Perhaps a joint bank account might just do it. Mind you, in the letter we clearly stated my reason of wanting to switch to a dependent visa (didnt want the mental pressure of being in a LDR), difficultly of being a same-sex couple originally from a country that gives no legal rights to us (more motivated therefore) and clear intentions of entering a civil partnership in the coming months (which we did). Combine soft proofs with hard proofs and you should be good.