MANILA - The Philippines' largest Moro rebel group has agreed to changes in a proposed law creating a new Bangsamoro territory in Mindanao in an effort to gain support from another rebel faction.

Areas included in the 1976 Tripoli Agreement with the Moro National Liberation Front (MNLF) may "opt to join" the Bangsamoro territory, according to the new version of the Bangsamoro Basic Law (BBL) submitted to President Rodrigo Duterte on Monday.

These areas cover 13 provinces and 9 cities, which may join the new territory through a plebiscite every 5 years.

Al Haj Murad Ebrahim, chairman of the Moro Islamic Liberation Front (MILF), said Tuesday he was hoping the "improvement" in the new draft BBL would be "acceptable" to the MNLF faction led by its founding chairman Nur Misuari.

"Naipasok na 'yung concern ng MNLF brothers," Murad told ABS-CBN News.

(The concerns of our MNLF brothers were included.)

The new option addresses the concern by the MNLF that "you are not giving up your claim over the 13 provinces under the Tripoli Agreement," said lawyer Benedicto Bacani, executive director of the Cotobato-based think tank Institute for Autonomy and Governance.

FLEXIBILITY

Misuari's group launched a bloody siege on the port city of Zamboanga in 2013, complaining that it had been left out in peace negotiations between the MILF and the administration of then President Benigno Aquino III.

Duterte promised to implement the MILF accord as well as the 1996 final peace agreement with the MNLF. He is talking separately with the Misuari faction.

"You need flexibility here, you need to be creative. It would be difficult if this becomes a zero-sum game, winner-take-all," Bacani told ABS-CBN News.

A new "delimitation" provision in the proposed BBL sets the periodic plebiscite every 5 years after its ratification.

The Bangsamoro territory will then be considered "delineated and delimited" and "no other plebiscite for expansion shall be held" after 25 years.

"You have 25 years for the Bangsamoro to expand and after that, then that's it," Bacani said.

The original draft submitted to Congress included no time frame, raising concerns over the "creeping expansion" of the proposed Bangsamoro territory.

"The concern before was when would (this expansion) end or was there any limit to it? Because in the end, it might cover the whole of Mindanao," Bacani recalled.

GEOGRAPHICAL AREA

A version of the bill in the House of Representatives later allowed petitions for inclusion to be filed only on the fifth and tenth year from the enactment of the BBL.

The "core" territory of the Bangsamoro will include the current Autonomous Region in Muslim Mindanao (ARMM), Cotobato City and Isabela City, and 6 towns in Lanao del Norte.

It will also cover villages in the towns of Kabacan, Carmen, Aleosan, Pigkawayan, Pikit and Midsayap, which voted to be included in the ARMM in the 2001 plebiscite.

Bacani said questions might be raised over the ARMM taken as a "geographical area."

According to the new BBL draft, the Bangsamoro territory will be established "if the majority of the votes cast in the entirety of the (ARMM) voted in favor" of the new law.

"(This) means if majority of the voters of ARMM vote to be included in the Bangsamoro, the whole ARMM region will now be part of the Bangsamoro," Bacani said.

"Politically, this means it would be easier for the whole ARMM (to be part of the Bangsamoro)."

The old BBL version covered majority votes in "each province and city" of the ARMM.