He admitted Wanna told him much, though not exactly what. Again backing to Caladan trilogy, one great thing Brian did in that book is to show how many BG de facto rebelled in those times because love and marriage - which is surprisingly consistent with later eras BG completely abandoning the ideas*, holding their sisters way more strictly and developing techniques like imprinting (and ultimately factoring in rise of Honored Matress).

*Iirc only BG that still did it openly later was Teg's mother and it was counted as incredible scandal, but she had reputation of witch among witches and nobody dared to oppose her. For the rest, exile on Buzzell awaited.