V15 - how do I redefine a generalized property or am I going mad

[ClockwiseMango]

Hi all,
EA and SysML relative newbie in the room so be gentle. I have searched the forums though probably very badly.

I am trying to create a generalization in SysML where I can modify the inherited property to be a specific entry from an enumerated list

I am expecting that if a create a parent block with a value property linked to an enumerated valuetype then a generalized child could then have that value property redefined to one of the enumerated valuetypes

I'm going to write everything:
1. on a BDD dragged on an enumeration
2. applied the valuetype stereotype
3. add three attributes choice1, choice2, choice3
4. on another BDD dragged on a block called it parent
5. created property called choice and type'ed to the enumeration valuetype above
6. dragged another block called it child
7. connected this child to parent with a generalization. head at parent and tail at child

if I click the property choice in parent I can redefine in the properties table and select an enumeration form the valuetype

Going to child I select in feature menu the property owned by parent and select redefine.
It creates a new property in child
if I then try to redefine that property to one of the enumerations all I get is the ability to select the valuetype not any of the enumerations

The generalization link
Source - Child block
target - Parent block
direction - source->destination
substitutable -  ticked

What am I doing wrong, is it broken or am I just slowly going mad

Thankyou as I am running out of hair