Jamie had stayed quiet. He really didn't want to give Regulus more ammunition and the man was too good with words not to turn anything and everything as a stepping stone to hurt the people he didn't like it. He was also very aware of what Regulus was doing. Others might not, but he knew Sirius enough to expect his reaction.
"Sirius, let it go," he said, softly. He put a hand on his husband's back, rubbing it gently. "Does it really matter who knows and doesn't? It's their child, and they can make whatever decision they see fit. Just like we did," he added.
He turned to Lily and James and smiled. "It is great, and Dad would have loved the news. He wanted you happy, and if there's anything I can do to help, then let me know."