EU national settling in UK with unmarried non EU partner

[fritzkohle]

I am a EU national and with my partner I have a one year old son who is an EU national as well. My partner is a non EU national.

At the moment my partner is legally resident in Spain, looking after my son. I lived in the UK for some 13 years, though have worked abroad for the last two years and am about to return to the UK.

I want my partner and son to join me. We cannot yet get married as I am still waiting for my the divorce of my 1st marriage.

Question: should my partner apply as an unmarried partner (settlement visa) OR as a non-EU dependent of a EU-national. (non-settlement visa)

The latter has obvious advantages, it is free charge. However, would my partner qualify as a dependent of an EU-national as we are not married, or will the fact that she is the mother of my son, who is an EU-national, be sufficient?