Trustee appointment

I have a DIY will under which W is appointed as sole Executrix but not a Trustee. H has now died and there is a NRBDT under his will. I understand that in the absence of an express Trustee appointment or any express powers to appoint in the Will, W will automatically become a default Trustee. Is this correct and if so under which Act/case law is this set out please? The W will need to appoint a further Trustee and I’m fairly sure this can’t be carried out under S36 TA1925 or S19 of TALATA due to minor beneficiaries which potentially leaves us with a court application under S41 TA1925 .

Shanti Palmer