The intecessions for the Liturgy of the Hours are discussed in the General Instruction. A few extracts:
“184. In addition, the conferences of bishops have the right to adapt the formularies given in the book of the liturgy of the hours and also to approve new ones, in accordance with the norms that follow. …”.
“186. In the intercessions at evening prayer the last intention is always for the dead.
187. Since the liturgy of the hours is above all the prayer of the whole Church for the whole Church, indeed for the salvation of the whole world, universal intentions should take precedence over all others, namely, for: the Church and its ministers; secular authorities; the poor, the sick, and the sorrowful; the needs of the whole world, that is, peace and other intentions of this kind.
188. It is permissible, however, to include particular intentions at both morning prayer and evening prayer.”
The General Instruction of the Liturgy Hours is at
ewtn.com/library/curia/cdwgilh.htm .