Merging of two firms into new one

Dear Expert, could you please let me know the procedure for merging of two firms into one firm, under Gst Act, and the closing stock as on the date of merging position, some of them are telling me that the closing stock of two firms have to be shown as sales to the new firm and sales tax has to be paid accordingly and input has to be claimed by the new firm, is it correct? and the closing stock will be crores of rupees and the tax will also be in lakhs, then in that case it is difficult to manage funds for making payment of sales tax and claiming the same in input tax is there any other procedure for integration of two firms and making a new firm thanking you, yours truly rajesh