We cannot help you until you share your code, specially constraint.

the code has grown quite large but ill try to compress:

class Order(models.Model):

order_line = fields.One2Many('order.line', ...

cost_center_line = fields.One2Many('cost_center_line', ...

amount_total = fields.Monetary(store=True, compute='_compute_amount')

amount_cost_center = fields.Monetary(store=True, compute='_compute_cost_center_amount')

@api.depends('order_line.price_total')

def _compute_amount(self):

for rec in self:

amount = 0.0

for line in rec.order_line:

amount += line.price_total

rec.amount_total = amount

@api.depends('cost_center_line.amount')

def _compute_cost_center_amount(self):

for rec in self:

amount = 0.0

for line in rec.cost_center_line:

amount += line.amount

rec.amount_cost_center = amount

@api.constrains('amount_total','amount_cost_center')

def _constrains_amount(self):

for rec in self:

if rec.amount_total != rec.amount.cost_center:

raise ValidationError('...')