How to get all files attached on potentials added since x days

How to get all files attached on potentials added since x days

Hello,

I need to retrieve the list of files attached recently to potentials .

I can retrieved files list for one potential 
https://crm.zoho.com/crm/private/xml/Attachments/getRelatedRecords?authtoken=mytockens&scope=crmapi&parentModule=Potentials&id=id_of_a_potential  

but i can not have the list of potentials that have new attachments (or modified or deleted) since the last x days for example

https://crm.zoho.com/crm/private/xml/Potentials/getRecords?authtoken=mytockens&scope=crmapi&lastModifiedTime=2017-08-25%2000:00:00   return  "There is no data to show"  because this query do not take in account the sub-objects

I take all good ideas.

regards

Gilles