Hi Pzafian (how did come come with this name?)
On the cross swivel in Quickstep may I fisr correct you. There shouldn't be any checking action on the 3rd step prior to dancing a fishtail. This will cause you to travel sideways and fall off your step. The weight should be fully committed onto your right foot. If anything there is perhaps an early rise out of the right leg in order to time the fishtail correctly. Is this perhaps what you meant?
As far as the tipple chasse is concerned, I'm assuming you are still travelling along the same LOD. If so then the turn is just a quarter. If you ended the cross swivel against the LOD the normal position to move into the Tipple chasse then the amout of turn is the same as if it it commenced from a back lock the normal basic figure precede.
Hope this helps.
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Steve Kelly