Step Child, NO solo responsibility but father approval

Hello

My husband is British and we want to apply for my spouse visa and my 8 year old daughter (his step)

My husband ticks the finances, accommodation and spouse visa criteria.

With regards my daughter, I do NOT have sole responsibility for the girl, but my ex has signed a legalised document in Brazil saying he is happy for her to come and live in the UK.

Reading immigration websites and advice, I'm confused as if this would be enough, as my understanding from the advice is even though he has given his written permission, without the sole-responsibility it is likely to be refused?

Any help, would be gratefully accepted
Regards

The link below explains what UKVI expect to see and circumstances covered.

immigration-for-family-members/sole-res ... 13087.html