Talking about children in an extended-family setting can sometimes be challenging in Japanese culture due to the highly developed system of grammatical marking for epistemic stance. Parents of a child typically hold epistemic authority regarding the child, which makes non-parent participants cautious about how they speak. At the same time, asserting oneself as more knowledgeable, especially in front of older parents-in-law, may be perceived as face-threatening. Drawing on videotaped, naturally occurring conversations, this study investigates how participants position themselves when engaging in talk about children. By analyzing conversations among participants with both intra- and intergenerational relationships, this study demonstrates how grammatical resources, membership category, and the participation framework contribute to the negotiation of family relations and epistemic status.