I am not working in MD, so therefore I am not 100 % sure about what is legally correct in your state....
It should be similar everywhere though.

In my state, if you are selling by owner, without Real Estate agency involved, you hold your own open houses
no problem....

If on the other hand you are using a listing agent/Real Estate Brokerage company who listed your property,
(and this is in my area.... ) during a Sunday open house to the public a licensed Real Estate agent has to be at the open house, as the visiting public may want to write an offer, ask pertaining questions etc., in that case it is usually the listing agent, or an agent from the very same listing office!

If on the other hand it is an open house for touring brokers/Real Estate Agents to preview the listing by themselves, anyone can hold that open house, but it is then closed to the public, open only to licensed Agents....

If you have a listing agent that listing agent should know the rules of their Real Estate Board/Law
If you are selling For Sale By Owner, you are good to go!

Good Luck to you, I hope this helps, but again I am not from MD.......
Just thought I share these details from my state with you.
Edith Karoline YourRealtor4Life!
Working always in the very BEST interest of her clients....
EdithSellsHomes@gmail.com

PS if you ever know of anyone who is thinking about buying or selling property in Chicago, surrounding areas
or anywhere in Northern Illinois, send them my way as they will receive first class real estate service
THKS!

If you are the home owner and selling on your own you should be fine, you have every legal right to sell your own home by whatever legal means you choose.
If you are related to or working for a licensed agent I believe it would be legal for you to 'host' an open house but you would not be able to answer, questions about the property, the owners or the sale. Those would need to be referred to the licensed agent of the owners. You should be able to hold the house open for public access, to hand out flyers and gather information for potential buyers for a licensed agent
The indication is that you are in Easton, MD? I do work and live in Easton, please do not hesitate contacting me if I may be of further assistance
410-924-0901 (C) 410-770-9255 (O) jbent@bensonandmangold.com

If you are the owner of the house and are selling it by themselves (FSBO) you can. However, I do not believe that it is legal. An Agent can have someone there with them to help hand out flyers and keep you company but to answer questions about the property.
Hope this helps.
Ania
AniaMiller@kw.com