Can I Share Merlin Project with My Family through "Share Purchases"?

Yes, this is possible. If you're using Merlin Project from the App Store and have family sharing enabled in your Apple account, you can share access to your Merlin Project subscription with up to five other family members.
Each family member uses their own account, so everyone’s experience stays personalized and private. The shared content automatically appears on the Purchased page in the App Store or iTunes Store.