Subform in Subform add record simple but confusing

[supa_sumo]

I have a Subform (SubB) on my main form sourcing its Parent ID from another subform(SubA) on the main form.SubB contains a Subform(SubC) displaying records with related information to SubA.i am doing this by using a Parent Child link between SubB and SubC.On SubB there are text boxes to add new records to the table displayed in SubC.When SubB refreshes the text boxes displays the 1st record from SubC.
I want these boxes to be blank(select new record) so that when a user wants to add a new record they can simply fill in the text boxes and hit the Add Record button which would then be displayed as a record in SubC.
Ive tried putting
DoCmd.GoToRecord , , acNewRec on Current but when i do that SubC does not populate.
Any ideas how i can cure this problem?

Ive tried to explain it as clearly as i can.really need to find a way round this so if you require any more information please do ask. Thanks

 

[supa_sumo]

After having a think, ive realised what i need to do. Instead of using SubB as a parent on SubC I need to make SubA the parent. So if I have

[frmInvoiceSub].Form![InvoiceID]

as link master field on SubB to link it to InvoiceID on SubA and SubC is a subform within SubB how would i link SubC to InvoiceID on SubA.

Hope sumone can help,
Sci