Sentence need fixing

[Bakkerbaard]

I'm going through the corrections from betareaders, and they all trip over the same words in one way or another. With your permission, I would like to present it you, because I have now stared myself blind on it.
I also believe I may have asked you this exact question before, but that was way back when I wrote it, and eventually figured I'd "get it later." It's later now.

With a sigh, she surveyed the scene that had unfolded here: Four security guards pointed cattle prods at an eighteen-year-old blonde with her hands in the air. Before she managed to approach her assumed niece, Lilith was blocked by Hospitality’s crew manager, Linda, who nervously tapped a tablet.

The problem lies with "assumed niece." I need a better, but still compact way, to formulate it.
The dynamics between Lilith and the blonde eighteen-year-old (Kayleigh) are as follows:
Lilith is a long time friend of Kayleigh's parents. Nothing more. No adoptions, godparenting, or anything official. She's just been a friend of the family for so long that she's sort of become Aunt Lilith. Most of us have got someone like that, right?

Readers who have read the previous books should be able to infer the meaning, but my betareaders keep suggesting this is not adequate wording.
I can't just leave it at "niece" either, because there has been some godmothering going on with someone else, and previously known dynamics have shifted some, but Lilith is really just an unoffical aunt.

 

[Hammer]

Can't you just put niece in inverted commas? Before she managed to approach her "niece". If you're in the know it would make sense, but even if not, it's clear that you're not using the word actually to mean a sibling's daughter.

 

[Naomasa298]

Show, don't tell. Include a scene, or a thought that explains the explanation early in the book, and thereafter, just use normal pronouns or a name to refer to her. In this scene, that just means replacing "assumed niece" with "Kayleigh".

 

[Dogberry's Watch]

I recommend "unofficial." The thing I'm gonna say is you mentioned the relationship is explained in previous books? So, readers who have previously read your stuff will already know this, and explaining again won't really be necessary, especially in this moment. "Unofficial" is what I use to describe my relationship to my best friend's kids. She just calls me Auntie Dogberry, though.

 

[CdnWriter]

Honorary niece? I know someone wrote a time off request to attend the funeral of a honorary uncle, not a blood relation but close friends with her parents, thus "uncle."

My first thought was actually "adopted" - there are unofficial adoptions and formal adoptions. I'm thinking where a parent is undergoing a medical treatment, like for cancer and arranges for a family friend to care for their child. There's no legal or permanent transfer of guardianship involving the courts but the friend is given and accepts the responsibility for caring for the child. Think of the issue when parents write wills (or should write...) and they name a guardian for their child in the event of their death, that type of relationship.