I am going to say this as respectfully as I can...
You are basing opinions on something that you aren't even sure about. There is trial testimony available, there are documents available. Kayla did NOT say anything to the counsellor about Brendan specifically.
Kayla gave a written statement to LE AFTER Brendan was arrested, and AFTER KK held his "remove the children from the room" press conference. If you want to go ahead and believe what she said then and not what she said at trial and has continued to say even now, then go ahead, it doesn't change the FACTS.
Here is the school counsellor's testimony:
http://www.stevenaverycase.org/wp-content/uploads/2017/02/Dassey-Trial-Transcripts.pdf#page=697
Q And what did she tell you?
A She told us that she was scared, urn, because her uncle, Steven Avery, had asked one of her cousins to help move a body.
Q All right. What else, if anything, did she tell you about that?
A She also said she was scared about going to the shop, urn, and she, specifically, asked if blood can come up through concrete.
Q All right. Now, was -- Did she identify which of her cousins may have been asked by her uncle, Steven Avery, to move this body?
A No.
Now, lets recall that there was a "joke" between MO and SA that Bobby overheard about helping to move a body. She was concerned about going to the "shop"... somewhere in the discussions over the years, I believe it was determined that this was something that Earl (her dad) said, but I will say JMO because I don't think that was something in the documents, it may have come from Kayla herself in later discussions. She talked freely on FB for awhile before KZ asked the family to stop. I recall her posting that Brendan didn't tell her anything and that Wiegert put it all in her head, I may even still have a screenshot of it or it's posted in one of the many threads here.
ETA: LE was reinterviewing all of the family members in February (right after SA hired Strang) IMO Brendan was the weakest link.