His ugly step-siblings not appreciating his getting the spotlight? His mother intervening.
“Prior commitments” makes no sense in this context.
As far as I know, he only has half-siblings, no steps.
His siblings are already delegates at large.
“Other family members - Don Jr. and his fiancee Kimberly Guilfoyle, Eric Trump, Tiffany Trump and her husband Michael Boulos - are also delegates at large for the state of Florida.
Ivanka Trump, who served as a senior adviser in her father’s White House, was the only Trump child not on the delegate list.”