It's of significance whether there is an ATC unit at the aerodrome.
If there is, then the aerodrome controller should issue instructions to maintain a 'safe, orderly and expeditious flow of air traffic' - things don't always work out the way they are planned and I would expect the controller to work with you in a case like this. Widening out your circuit may be a good way odf resolving your immediate problem but may cause a problem for those that follow you. Of course the Rules of the Air for avoiding aerial collisions must always apply if there is an immediate risk of collision.
If there is no ATC, then the Rules of the Air apply and they include conforming to the existing traffic pattern (which is commonly taken to mean always fly a standard overhead join unless something else is promulgated) and the one about the lower aircraft having right of way.