600k in equity, need advice

[Derick Hanna]

A close family member just had their home appraised and it came back 855k. They have 600k in equity. I am relatively new in my real estate journey and my family member has no experience other than renting 2 ADUs on the appraised property. I currently have a 4plex that I got with the VA loan that I am house hacking. My plan was to use the rest of my VA eligibility to get another small multi family next. My family member wants to get into real estate and is open to lending or partnering with me. Should they HELOC or cash out refi? Feels like there is a big opportunity here. Neither of us want to waste it. Ideas/advice would be great.