@Babal I am no expert and really find it difficult to manage 4/5 applications. However, with my little understanding here is my chhoti si contribution if it helps :
1. Make data base of all the 20 applicants in Excel worksheet (or manually in a register)
By the way, who are these 20 people? Your family members, friends, employees, neighbours, gardener, presswalah ... Well, it does not matter if you have their consent to operate on their behalf and are ready to share credentials.
2. Open bank account for each one of them, say Kotak 811 a/c (just an example, I have no affiliation). Each one should have PAN, Aadhar, Phone as bare minimum requirement. Also create e-mail IDs for them.
3. Next step is to obtain demat account for each one of them. Choose any discount broker (say Zerodha). You will require bank account nos. and other credentials as mentioned in step 2
4. Demat accounts once ready can be used for applying IPO. Ensure IPO is applied with unique PAN and respective bank a/c only as third party are liable to be rejected. For this, you need funds to be made available (atleast Rs 15K in each account).
And lo, you are all set to go.
Keep recording data and activities in Excel sheet for ease in tracking.
Please note above inputs are not to be construed as any legal advice. Please study and take your own decisions.
All the Best 👍