Ownership Dispute Youtube Channel

[friday13th]

In 2013 a relative of mine set up some youtube channels for videos to try and earn money. He approached another friend who was into gaming and asked if he would like to set up a channel for gaming. This friend agreed and opened a Google plus account and Youtube channel with both their phone numbers and shared the details and password with my relative. My relative went on to make a few gaming videos with his friend using a cheap camera they had bought. Eventually my relative had to buy much better equipment to upload the quality they needed. The gaming videos continued to be filmed, edited and uploaded by my relative using his family's computer, but the channel wasn't very successful. My relative decided to start making videos which did not involve gaming,but the friend was not as keen on this so most of the time did not show up to film or contribute. In the end my relative started to make videos on their own and promote the channel using Facebook and Twitter. Their videos started to get noticed so they signed up with a company that would pay income. As soon as the friend became aware of the income they wanted 50%. When the finances have been checked the videos in which the friend appeared have hardly earned any income, but the friend still wants 50% of all the money and on top of this they owe my relative money. My relative just wants to keep the channel and walk away from the friend and pay them 50% of what the joint videos earned less what the friend already owes. but the friend is still demanding 50% of everything and keeping the channel for themselves. How does my relative stand can anyone help?