Grantor of Living Trust is deceased do I as executor need to establish an EIN

Our parents in 1996 created a living trust in Texas using their SS#.  The beneficiaries are their four children with me being the Executor of the trust.  Father passed in 2006 and mother the last surviving trust member passed January of 21.  All assets are held in trust.  In order to report and distribute assets as Executor am i required to establish an EIN or can I continue to report using the Grantors SS#?