Usage of Adobe for Multiple Digital signature, & programatically (C#) adding content to placeholders

Usage of Adobe for Multiple Digital signature, Verify signatures & programatically (C#) adding content to placeholders

Hello All, 

I have a requirement where a specific template is used to create place holder for dynamic data and also place holders for digital signature. 

As the data is filled dynamically my system whould ask the user weather they want to sign the documnt and then the signed document to be preserved After the sceond user review he/she should be able to sign the document. After the final signature My tool should verify all the signatures are valid .

Am hoping Adobe SDK is best for this implementation as it involves pdf and multiple digital signature .

It would be very much helpful if smeone can get the relevent dpcuments for placeholder creation in PDF , How to digitally sign from C# program and How to verify the signatures. How this to be stored to hold the validity of signatures.