Second Administrator - minors are sole beneficiaries

A colleague is dealing with an estate where the deceased died intestate. He was not married.
He has four minor children with two mothers. One of the mothers (and their children) live abroad and is happy for the other mother to deal with the administration of the estate.
Does the mother who resides in E & W have to make an application under 32(2) NCPR to appoint the deceased’s mother (grandmother of all of the children) as second administrator? I assume this would just be a statement of truth?
Or can she just state that the mother abroad is unwilling to take the grant and nominate the grandmother in a statement of truth?
Thank you