I share 2 ponds with 2 different neighbors. I believe it to be such that from a boat, you have access to the entire BOW. If fishing from shore, you only have access to your property. I fish tons of streams that back up to others properties and have had the same arguments. They usually don't go far as I legally carry a side arm, lol. State law says that you are not trespassing unless your feet have set foot on actual ground on their property. I can float in inches of water, but if I come across a riffle and have to walk my plastic boat through, I am then trespassing. IMO I would be cordial and invite them over for a non pond related event, party....be more than property share owners. Not pointed to you, but IMO people don't know how to be good neighbors anymore. I come out when I see my neighbor tackling a project by himself and offer my help/tools.

God has blessed us with this day, what we do with it is up to us.