Help! Father of the bride suit

First, let me start by saying this was my fault. I wasn’t clear. I have been procrastinating about wether both my father and step father would walk me down the aisle. Also, my step father doesn’t spend money on clothes. He’s a very practical man. If I would have them walk I would just allow him to wear his black suit pants that he already owns and a button up shirt. But then I mentioned to my mother that maybe they should be in a charcoal grey. Our wedding colors are navy, burgundy, grey, and gold. So he started looking for charcoal grey suits online. And I was like great. He can wear a full suit... grey. Well he ordered a grey one online with the help of my mother and it didn’t fit well so he sent it back. He then took it upon himself to go suit shopping... alone. Which, I know I have not approached this with much formality so that is my fault. Well he came back with a suit that everyone in the store said looked great on him. He feels good in it. And it was only $150. He’s so proud he handled it by himself. But... it’s black. What do I do?! If they are both walking me, does that mean my dad needs to wear black as well?! If they are wearing black suits should they wear white shirts? If they are both wearing black suits with whit shirts and by groom and his only groomsman are in navy suits with brown shoes, with the dad’s not look too formal? I don’t want to hurt my step father’s feelings. But with 2 dads in black and 2 guys standing up front in navy(groom and best man) is this going to look ok? My dad asked if he should get a grey suit and I don’t know what to tell him.