i think Dharmesh's non reaction to the situation might be beause he had no choice like now where he has to put up with Manav while working beneath him. And about Archu saying it is her son. This type of dialogue is said all the time, to show big heart, mahaanta, etc. It might have also been said deliberately to mislead the viewer into thinking it is Armaans son just to test the waters and sense viewer reaction to the possibility of that scenario and if it is not well received, they can change track at the last minute. It's kinda open ended right now and the writers can explain away all these dialogues by puttiing it in full context. One line (this is my son) does not conclusively show how the whole situation came about. The next sentence in Archu's monologue COULD be, Soham meri zimadari hai. Woh Mera Beta Hai JAB TAK MADHURI LAUT KAR NAHI AATE HAI. Just another possibility.