There were so many things that were infuriatingly implausible about the whole thing. It's a shame because it had the makings of a great plot. If only they'd focused on what really might have happened in that scenario, instead of turning it into an outlandish murder thriller.
Would the family courts really have rules that Teho should live temporarily with Miles and Lucy on the basis of such flimsy evidence of alleged poor parenting when clearly all the allegations were coming straight from Miles who had an obvious agenda and they'd never been on SS radar for anything before? 
What was all that about the dead brother in Scotland? We never even found out whether Miles was implicated, or why he didn't speak to his mother after his brother died. And her turning up in the court room, only to walk out and not even have a conversation with Miles? Just odd and unbelievable.
And are we really to believe that Lucy was so desperate to protect her newborn son that she's swap him with someone else's and risk that child being harmed, rather than simply leave her controlling husband? I mean come on.
And that Maddie would just take all this on the chin and say 'Okay fair enough, well let me help you evade justice by covering up Miles's death for you. If we are caught we'll all go to jail and lose both the boys, but never mind that.'