When we add a new record N to an one2many tree view from an existing record X form, during the onchange() on the one2many comodel, the cache of the N.one2many contains only the new record X (the siblings aren't in it). Because of this, the result of compute methods may be incorrect and the form won't be updated accordingly. See https://github.com/odoo/enterprise/pull/52957 for a concrete example. Technically, this is due to _update_cache() forcing the inverse field value to the single value of the new record ("not cache.contains(inv_rec, invf)" is True), instead of also considering the original values (which is properly done by Field._update()). closes odoo/odoo#146778 Related: odoo/enterprise#53298 Signed-off-by: Raphael Collet <rco@odoo.com>