Insert custom app into related document

Hi Guys,

I have created custom app named ‘Design Files’.
When quotation been created and if there is an files been upload, A record of ‘Design Files’ with quotation id will be created. Is it possible to add in custom app ‘design files’ to related documents region?
Once click, it will link to listing of ‘design file’ filter by quotation id.
Appreciated you help. ^^