Grammar and sentence structure

in the following example:

John bought the book of poems that Tom told him about it last week.

so, here the CP(that Tom told......) is it a modifier to the DP(the book of poems), if so, we should consider it when we are drawing a tree as an adjunct, which means must be sister to x-bar dominated by x-bar. or as a complement, which means sister to lexical category dominated by x-bar.