Undertakings are cumulative. So, where an undertaking has been given and the amount of that undertaking is to be increased, it is best to give a second undertaking just in respect of the increase. Where the other side requires one undertaking for the entire sum, this must either be conditional on the release of the first undertaking or we must first be provided with a written release of our earlier undertaking(s) (such release may itself be conditional on our issuing our further undertaking).
Any further undertaking is treated separately, and the relevant procedures will apply.