Pena will face the winner of Thursday’s clash between former team-mates Nkazimulo Zulu and Charlie Weyer for the EFC Africa bantamweight title.
“Demarte has dominated at featherweight, despite being physically smaller than most of his opponents,” said EFC Africa president Cairo Howarth.
“He’s going to be a monster at bantam, and undoubtedly the biggest threat to Thursday’s newly crowned champion.”
Howarth had campaigned for a fight between the number one and two featherweights since they turned down an offer for twice their usual fight fee in November.
He warned Pena last week that he would not be offered another bantamweight contest unless it was against Allen, the No 1 contender, or Allen was defeated by someone else.
Pena, however, said the fight would create division in their training group and one of them would probably have to leave the camp, as was the case between Zulu and Weyer.
Howarth met with both fighters to discuss the deadlock, and the decision was made for Pena to step down.
If Pena wins the bantamweight title he will be the first EFC Africa fighter to have been champion in two different weight divisions.
Meanwhile, Allen’s opponent for the vacant featherweight title had not yet been announced, but he was pleased to be given a chance.
“I can’t wait. For me every fight is an opportunity to test and sharpen my skills,” Allen said.
“The added pressure of a title fight is what I want, what I train for every day.”