Wrong-way collateral and endogenous margin

A ₹10 lakh MTF position is fully funded by the broker; the margin is met by pledging ₹6 lakh of shares at a 25% haircut. $m = 27.5\%$. (a) At what fall in the funded stock does a call come if the pledged shares are unaffected? (b) And if the pledged shares are the same stock? (c) In case (b), suppose the stock's VaR margin rises with volatility so that $m$ becomes 35% once the stock has fallen 10%. Where is the trigger now, and what does that mean for the position?