Template:Amending security interests
If you amend a security document you risk the argument that you have terminated the old security interest and created a new one, thereby re-starting any voidable preference period, potentially invalidating any previously registered charge at Companies House, and of course relegating your interest behind those of anyone who has registered a security interest over the same assets in the intervening period.
Some of these risks have been de-complicated by the financial collateral regulations (insofar as they've done away with registration requirements for financial collateral arrangements), and while this is a bit of a mine-field, basic common sense should avoid anyone but the most headless chicken-licken standing on any landmines.
For one thing, to run any risk you have to actually be amending the security interest itself, rather than other related legal or economic terms. So, if you have — ooh, say a prime brokerage agreement which contains a charge but a lot of other stuff besides — you are (in the humble opinion of this bear of little brain) most likely to be amending other things and not the actual charge provision, which tends to be dull and workpersonlike. You may tweak rehypothecation limits, financing rates, transaction terms and so on — but the security package will remain intact.
Magic wordsTM
No amendment provision would be complete without the following magical incantation: