併合 （ヘイゴウ） merger, joining into one, amalgamation, melding, merging, annexation, absorption

並行 （ヘイコウ） going side-by-side, going abreast, running concurrently, occurring at the same time, keeping pace with

合わせる （あわせる） to match (rhythm, speed, etc.), to join together, to unite, to combine, to add up, to face, to be opposite (someone), to compare, to check with, to cause to meet (e.g. an unpleasant fate), to place together, to connect, to overlap, to mix, to combine, to put blade to blade, to fight