Display three picklist dependent on each other (while editing one pick list other two should get ref

Please consider this data model, 
Account –> Opportunity –> OpportunityLineItems 

I have account as my master model. so according to my understanding I can pull only account field in layout. 

now, the requirement is once I have to display related opportunities in picklist and once this picklist selection is changed, I have to render another picklist which will contains OpportunityLineItems of selected opportunity. 

I am able to achive first part to show all opportunities related to that account in picklist through custom render, but not sure how can I render another picklist which contains only those opportunityLineItmes related to selected opportunity.

we are new to skuid and any code sample will be very helpful.

Thanks in advance.  

Can anyone please address this question, even I am having the same issue.