Hello all – 
I am using v.16, making customizations to the CRM module – adding attributes to leads - Twitter handle for example, so I'll use twitter_acct from hereon. 

I am doing it via inherited views and models.

I was able to successfully create the views to display twitter_acct, store it and edit it in crm_lead table.

I was also able to add the appropriate column in res_partner.

I am failing to propagate the value of twitter_acct from crm_lead to res_partner while the record in res_partner is created when the new crm_lead record appears. 

My guesswork:

1. in inherited crm_lead.py I added 

CRM_LEAD_FIELDS_TO_MERGE, PARTNER_FIELDS_TO_SYNC

which contain the twitter_acct field.

+ added the twitter_acct var to 

_prepare_customer_values res{}

+ copied 

_prepare_values_from_partner and _merge_get_fields

since they are using 

CRM_LEAD_FIELDS_TO_MERGE, PARTNER_ADDRESS_FIELDS_TO_SYNC

2. in my inherited res_partner.py modified default_get

if lead:
    rec.update(
        phone=lead.phone,
        mobile=lead.mobile,
        function=lead.function,
        title=lead.title.id,
        website=lead.website,
        street=lead.street,
        street2=lead.street2,
        city=lead.city,
        state_id=lead.state_id.id,
        country_id=lead.country_id.id,
        zip=lead.zip,
        twitter_acct=lead.twitter_acct,
    )

No luck. Twitter_acct does not propagate.

What am I missing?