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Hi Murali,
1) If you are conversant with TALLY ERP 9 then it should help you as to how to open an Acctg.Filing System/ A company's A/c. You know you can maintain accounts of all three co. at a time in the same Tally A/c. Open Co.A, Co.B, & Co.C and so on. Start creating required ledger heads and start entering the transactions. It's needless to elaborate step by step entries in Tally to a Tally literate like you.
2) If Tally a/c is in operation no need to maintain separate registers, everything you can have in it.
3) If you are not able to create a separate Assets register in Tally. Calculation of depreciation is also easy if you create masters like assets description, rate of depn. applicable as per laws/acts applicable there. And depreciation rates various depending on type of assets, usage, expected life of use etc. The Companies Act/IT Act in India is different than what is applicable in Dubai, so obtain all these guidelines and it may be necessary to consult competent authorities in Dubai or CFA if any in practice there as I'm not conversant with Dubai laws
4) If you use Tally Software no separate vr.no. would be necessary as you know Tally software assigns vr.no. automatically.
And in Tally software P & L A/c, Balance sheet, all linked ledgers, cash book etc. is also automatically updated as and when you make an entry and for every entry. You can have all the books, ledgers, PL, BS all together at any time for every entry/date.
If you are not able to begin better take hands on training on Tally from Tally licensed trainer or buy a Tally guide which will help you to do all by yourself. There are Online portals available to train you. Try them. There are lakhs of P & L A/c, BS of various companies available in those co. web sites, search and see for yourself. If you still what the formats I will provide them. All the best.