Relation between two columns is not woking

Dear all,

I am currently developing a pipeline for the sales team. I want to analyse number of leads, opportunities and sales orders for a point in time.

Leads and opportunities are in the same table, which is called crm_lead, whilst sales orders are in a tables named sale_order.

I want to track those sales orders that came from opportunities. In my database, I have two "types" of relation between opportunities and sales orders:

1. One opportunity transforms into one sale order.

2. One opportunity transforms into multiple sales orders.

I have a column in sale_order named origin, which gives me the opportunity id in the following way:

I managed to separate the id number from the opportunity and now I have a new colunm, named id_opportunity, with only the id number.

Afterwards, I created a relation between sale_order [id_opportunity] and crm_lead[id], in order for PowerBi to track those sales orders that came from an opportunity. 

The problem is that when I create this relation, those opportunities that have multiple sales orders (type two) disappear, and are not counted correctly as sales orders.

Here find attached an example:

I had two sales orders the last 1th July 2019. One of them came from the opportunity with id=2295, whilst the other came from the opportunity with id=2641. 

The opportunity with id=2295 has another two sales orders attached, all of them in different dates (corresponds to type two)

On the other hand, the second sale order, with opportunity id = 2641, has only one sale order attached.

When I enable the relation following relation: sale_order[id_opportunities] and crm_lead[id], and I specify it as many to one, the following happens:

Could you help me fix this problem?

If anything is not clear, please feel free to ask whatever question you need.

Thank you very much in advance,

Sara.