Sounds like you're just making more work for yourself. Seriously, break down that list of action into shorter sentences - as you have it, it is a list and frankly, as an outsider you've lost me even on a content level, let alone worrying about the pronoun. I don't care which woman is doing what because I cannot follow the action. And then in the shorter sentences, simply mention the characters' names. It's not tedious. And tedious is still better than confusing, trust me.
The trouble with the injured arm comment is that it is too close to friend - it's modifying the wrong thing. Always keep it close to the subject it's modifying.
Then are sentences such as the following too confusing and shouldn't exist? Amanda rolled over, relieving Sarah of her weight. Amanda rolled over to relieve Sarah of her weight. What would be a clearer way to write it?
Amanda rolled off of Sarah, who was grateful for the sudden weight loss. Amanda rolled off of Sarah, who sighed in relief. Amanda was heavier than she looked. With two in a sentense sometimes a few more words are needed to clarify the action. Even a sentense following can help explain some of the action.
I went to reply to this but it seems that you've deleted your question. Anyway, it was fine as it was. There's no confusion because of your use of conjunctions and commas. Remove those and it will suggest the opposite. There are other errors, but I'm assuming that is because this is a first draft.