PLS Tally of number of Shortsold Shares needing to be brought back, page-238

......I am beneficial so it is a no brainer what happens to my money if they go bust as I do not own the shares anyway, margin likewise (as Spacewalker says)........if my beneficial goes bust then it is gone to me anyway........the wording is the giveaway that peeps agree to......words like "equity substitution" and "third party transfer"........this means they can transfer your asset as long as they get collateral for the trade period....if you put a sell order on your shares then they are removed from the available shorting shares as they are not able to be guaranteed for short delivery as part of a transfer contract....
Your questions are valid and should be directed to your broker for a situation specific answer....or if you are Issuer Sponsored then to the Registry for your holdings.