Dear Radima,
Though u can't escaped from law, but from my point of view the total scenerio, as on now, depends upon your approach. You have not shared location and legal status of your com.
If the work done by employees is in accident prone area or hazardous nature, u must go for ESI.
But if not like that you can avoid. As stated by u, 7 are retired persons/s. If u exclude them the strength will b only 8 (Less than prescribed limit).
You can hire them on Contract basis (Being Professional). For that you have to engaged them thru a Legal Agreement. Their employment nature should be mentioned as Expert. They will raise monthly bill as Fees for their Service and you will pay them after TDS deduction.
Pls be noted don't allow them any other benefit like, Leave, Bonus, Mobile Re-imbursement etc. Else they can claim all employee benefits.
But this is a temporary solution, if your company grow, you have to go for ESI, EPF etc. If your budget allows go for that immediately.
For better controlling & regulating, seek some expert/s services.