## Issue:
When computing the product tree, the system would use `_bom_find` to find the BoM. However, it's possible to have multiple BoM for the same product, and the user should have chosen which BoM he wants to use. `_bom_find` ignores the user configuration in MPS, and simply select the first (oldest) BoM in the list. This means that the components in the MPS would not be correctly updated.

---

## How to reproduce:


https://github.com/user-attachments/assets/c7e6f4d4-332a-4e2b-a40a-1b831daeb6c8


- Create Products FNS & CMP
- Create BoM for FNS without bom line (V1)
- Create BoM for FNS with CMP in bom lines (V2)
- Add FNS to MPS using bom V2
- Set Forecast Qty of FNS to 10 
- => Indirect Demand Qty for CMP is not shown (because it's 0)

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## Test Result without fix:
```
2026-03-05 15:00:24,601 52396 INFO oes_test_18.0 odoo.addons.mrp_mps.tests.test_mrp_mps: Starting TestMpsMps.test_indirect_multiple_boms ... 
2026-03-05 15:00:24,742 52396 INFO oes_test_18.0 odoo.addons.mrp_mps.tests.test_mrp_mps: ====================================================================== 
2026-03-05 15:00:24,742 52396 ERROR oes_test_18.0 odoo.addons.mrp_mps.tests.test_mrp_mps: FAIL: TestMpsMps.test_indirect_multiple_boms
Traceback (most recent call last):
  File "/home/odoo/Odoo/src/18.0/enterprise/mrp_mps/tests/test_mrp_mps.py", line 1556, in test_indirect_multiple_boms
    self.assertEqual(forecast_cmp['forecast_ids'][0]['indirect_demand_qty'], 10)
AssertionError: 0.0 != 10
 ```

---

OPW-5979738

**Steps to reproduce:**
- Install Expenses
- Activate "Incoming Emails" in the settings
- Configure the expense Alias
- Configure an "Incoming Mail Server"

- Create a Branch for a company
- Create a User:
  * Email Address: [an existing email address]
  * Allowed Companies: [the parent company + the branch company]
  * Default Company: [the branch company]
  * User Types: Internal User
- Create an employee for the user in the parent company

- From the email address, send a PDF to the expense alias

**Issue:**
The expense is not created in the database due to a UserError: "Incompatible companies on records".

**Cause:**
When the email is received and treated, the system tries to create an expense.
From the email address, it retrieves an employee that is linked to the expense.
For the company of the expense, if a user is linked to the employee, it takes the default company of the user.
Otherwise, it takes the company of the employee.
In this case, the company set on the expense is the default company of the user (i.e. the branch company) and the employee set on the expense belongs to the parent company ; which triggers the UserError during the company check.

**Solution:**
Always use the company of the employee, even if there is a user linked to the employee.

opw-5346809




---
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Currently, in the batch payslip wizard, the 'Salary Structure Type' is determined by the first contract found for the employee.

### **Steps to Reproduce:**
1) Install Payroll.
2) Create an employee with two contracts:
-  Contract A: Expired, From DEC 1st 2025 to 31st DEC 2025, salary structure as 'Employee'
-  Contract B:  Running, Starts from Jan 1st 2026, salary structure as 'worker'.
3) Navigate to Payroll>payslips>Batches and click 'Generate Payslips'.

### **Observed Behaviour:**
The column displays the Structure Type of Contract A(Expired): `Employee`.

### **Expected Behaviour:**
The column should display Contract B(Running) in the Structure Type column: `Worker`.

### **Root Cause:**
The `structure_type_id` field was defined as a related field on `contract_ids`. Due to this, it always fetches the first record based on the default sort order.

### **Fix:**
Replace the relation of structure_type_id with `contract_id`. To ensure running contracts (state='open') are recieved, regardless of their start dates.

**opw-5311933**