Per Terms of Service, it's not even allowed to give your login details to someone else, so I'd recommend continuing with your own account from now on. I had a similar situation when I was deciding which of my accounts (PS4 or PC) I would set as my cross-save main. On one hand, I had much more history with my PS4 account, but on the other, I had earned many more seals and triumphs on PC. I went with my PS4 account, solely due to history and now I have almost caught up with my PC account's progress. I know it's a big task, but in the end you'll be happy that you made the switch.
I would say do yourself a favor and get the game on your own account. It's the best option for now and the future. You can either start fresh with New Light or purchase your own Shadowkeep and/or Forsaken Complete Collection now to get started (base game and first 2 expansions are included free either way). You'll leave behind all the stuff you have now, but you'll have control of everything with now worries what else your family is doing. And when Shadowkeep launches, you'll get automatically boosted to 750 power.