seek professional help. My opinion is that you have a partnership that requires filing form 1065 which for 2019 was due 3/15/2020. now being about 7 months late with 4 partners, the late filing penalty is now over $5,000.
from IRS form 1065 instructions
Partnership
A partnership is the relationship between two or more persons who join to carry on a trade or business, with each person contributing money, property, labor, or skill and each expecting to share in the profits and losses of the business whether or not a formal partnership agreement is made.
The term “partnership” includes a limited partnership, syndicate, group, pool, joint venture, or other unincorporated organization, through or by which any business, financial operation, or venture is carried on, that isn't, within the meaning of regulations under section 7701, a corporation, trust, estate, or sole proprietorship
