I haven't used surrogate EFT with affirmations yet. But I used it with my family successfully several times, for example one night my daughter was coughing so I tapped on her imagining the tapping, half-asleep, and she just stopped coughing after 2 rounds. Or on the phone with my father (he would not tap on himself - no way!), this time I was tapping on myself, but he agreed to be helped. I think it is necessary that they seek help, tapping for someone just because we decide that they should be helped is not a good idea in my opinion.

There are different opinions on this. Gary Craig's opinion is that we have no problem thinking or sending negative judgements and criticisms towards others we have issues with but when we think about sending healing or love we need their permission. We can always intend that we only do what's for their highest good. Another option if you know how to muscle test is to ask for permission from their higher self and see what answer you get.
Quantum physics has proven that our energy affects all energy around us so that just healing ourselves of negative energy will then affect the world around us, so if nothing else, focus on your own healing.

I agree with you, Cindy, muscle testing for the "permission" is a good option. I did that once when my father-in-law was taken to hospital. I needed guidance to know how to help him. The answer was that I should not tap for his healing, but I could help him pass away. And he did in a couple of days.
Apart from that, I prefer helping people who ask for it....