I struggle to make sense of this. Why would she prefer a feminine singular pronoun is some contexts, but a plural one in others?
Also, "she" and "they" are both subject pronouns. Using "they" as an object pronoun is not correct.
Example: When the alarm clock kept ringing, I went to wake they up.
She/they can also be referred to as her/them. Also in this context they is considered a singular pronoun. I would suggest looking up “they/them” pronouns. There’s a lot of resources educating on the subject.
In short, they/them pronouns are used when one identifies as non-binary (neither identifying as solely male, solely female, or either). The use of she/they or he/they pronouns usually means that they identify as both that specific gender and as non-binary. To quote one person who also identifies as she/they in an article regarding the topic, “I identify as a woman, but also as nonbinary. I don't feel womanhood tells my full story, but I'm not fully divested from it, either.”