plan, deliberate
謨 centers on careful thought before action: making a plan or deliberating over a course of action.
謨 combines 言 (speech, words) with 莫, which likely contributes the sound and may suggest a broad or large-scale deliberation. The exact historical development is uncertain.
Words (言) combined with the broad, expansive shape of 莫 suggest talking through a big plan or deliberating carefully.
For ボ, imagine a group planning around a big board: board -> ボ, and they deliberate over the plan written on it.