Ava's suggestion was heard by Madam Moreland. She originally liked Max Davies, and after the Davies' proposal, Lynette Moreland and Max Davies' engagement was more or less settled. It wouldn't be impossible to set an early wedding date.
As for Ann Chapman and Mia Moreland, Ann Chapman had been clear from the start that he didn't like Lynette. In fact, over the years, he hadn't even given her a chance. Madam Moreland didn't really intend to oppose it; Ann was a fine young man with good family background and character. Madam Moreland just couldn't digest the fact that both her granddaughters liked him.
If Ann Chapman had been involved with Lynette before, hurt her, and then came to mess with Mia, it's unlikely that anyone from the Morelands would speak for Ann Chapman, let alone allow Mia to act recklessly.
Given Lynette's feelings for Ann Chapman, who knows what she might do afterward. The best way would be to divert her attention.
