IHTM35085 | How many variations can be attempted?: link between s.142 and s.144
From HM Revenue & Customs · Inheritance Tax Manual
You may accept that
there can be an variation or disclaimer after an event, such as the exercise by trustees of powers of appointment and advancement, and
an event after an variation has created a discretionary trust, or a disclaimer has caused property to be added to a discretionary trust set up under the will.