The DMC seems a little nervous skirting the issue of adapting Roman Missal prayers for children. With good reason, I’d say. Let’s read:
50. The priest is permitted to choose from the Roman Missal texts of presidential prayers more suited to children, so that he may truly associate the children with himself. But he is to take into account the liturgical season.
51. Since these prayers were composed for adult Christians, however, the principle simply of choosing from among them does not serve the purpose of having the children regard the prayers as an expression of their own life and religious experience. [See Comme Le Prevoit 20.] If this is the case, the text of prayers of the Roman Missal may be adapted to the needs of children, but this should be done in such a way that, preserving the purpose of the prayer and to some extent its substance as well, the priest avoids anything that is foreign to the literary genre of a presidential prayer, such as moral exhortations or a childish manner of speech.
Most guys prefer to adapt their own prayers, but I have done some of this kind of work with them and with children. You really need an understanding of the genre as the DMC says. Any comments, especially from the clergy out there?