Increasing the length of a string field in a structure of a standard odata service

Hello,

Their is particular requirement that I have been working on past few days. Requirement is to increase the length of a structure field which is a part of a standard Fiori app. The structure of (Entity type field )odata service must have a max length specified which is currently 0 in standard.

Since the field that I am trying to increase the length is a part of a standard I tried to create a Z structure of the same and tried to increase the length of it. Then I tried to delete the entity type and then added it with the custom structure and regenerated the entire thing after adding all the navigation,referential keys and associations. The configuration is exactly the same as it was with the standard except that the custom Entity type field has a length specifed. When I run the service it says that

"Association name ""ABAP field already exists"

Can you please let me know if the approach I am following is right? Also please let me know how possibly I can achieve this requirement.

Note: For some reason since its a standard service redefined in segw I am unable to change the er entity type. It still has the standard structure referenced.

Thanks,

Deepak.M