I believe this is a duplicate question, so to be sure you get an answer, I'll repost here as well.
The situation you're discussing is something that's covered in case law. The Aranda-Bruton issue is where one co-defendant gives a statement that incriminates them, but also implicates their co-defendant.
If the prosecution intends to use the statement, it must be sufficiently redacted to exclude mention or indirect implication of the other defendant or the second defendant must be severed and allowed a separate trial.
If the prosecution does not intend to use the statement, then it won't be a ground to sever off the second defendant.Ask a similar question