combine
幷 centers on bringing separate things together into one: combining or uniting. The idea is straightforward, with no major distinct sense clusters.
幷 is an older form of 并, which historically depicted two people standing side by side, conveying the idea of combining or joining. The modern form 幷 is a variant that preserves this meaning.
The top 丿 looks like a hook pulling together the two horizontal lines of 干 below, as if combining separate parts into one unit.
For ヘイ, imagine combining two halves of a broken plate with strong glue: the glue is like 'hey' (ヘイ) holding everything together.