grammar - ではと - is this a particle?

それは、玉座に繋がれた真祖の姫ではなかった。
彼女は今でもあの間に繋がれたままである。
これは彼女の内面に潜む、彼女と融け合う事を待っている彼女に他ならない。

「はじめましてブリュンスタッド。
こうしてお話をする機会が回ってくるとは思いませんでした。
なにしろ貴方があの様子では、受け継ぐのは姉君ではと危惧していたものですから」

This isn't the princess of the true ancestor chained to the throne.
She is still chained there. This is what is dwelling inside her and is waiting to melt with her. Honored to meet you Brunesteid.
I did not think I could meet you like this and talk to you.
At any rate if you are in that condition, if it's that sister I doubt that inheriting is possible.

Or since he was speaking about waiting to melt I think

At any rate if you are in that condition, I doubt you can take over your sister.

I think:
ではと
では=Used before a negative consequence or something that is not favourable
と=Quoting particle

I looked for definitions of the words and found that:
受け継ぐ:前の人の仕事などを引き継ぐ。また，人の性質や志などを引き継ぐ。継承する
姉君:姉を敬っていう語。姉上。
危惧:うまくいかないのではないかと，あやぶむこと。危懼

I understand these 3 definitions and I tried my best to understand how the grammar works in the bold sentence.

Edit: I thought 姉君 could be used when addressing older girls
so

At any rate if you are in that condition, i doubt that for you it's possible