Connaught theatre, Worthing Balloons meet the sharper points of competitive parenting over a weekend of back-to-back kids’ parties, in this broad comedy of social mannersSome of my most traumatising experiences have come hosting children’s parties: the Wardrobe Ensemble’s new show should come with a trigger warning. This devised play pitches us deep into the parcel-passing, E-number-addled tantrumscape of a wee…