If I guess-understand right:

1. the amount to discount was the 155$, that got capped to 99€ in the first case ?

2. and "Incremento por Alta de Socio General y Asociado" is a negative promotion of -100€ ?

3. and in 2nd case, you increased plan value from 99€ to 156€ ?

In CBSubs promotions, there is a "safety check": "do not allow a discount to go further than value to discount, so that we don't go below zero", which probably gets the result you see.

However CBSubs is able to compound different promotions, using the previous sub-total of the basket with promotions applied, using the Discount priority.

Assuming my guess is right above, to obtain what you want, you need to give a different "Discount priority" to the 2 promotions:

Make first promo of -100€ priority 1
Make second promo of 155€ priority 2.

Then the first promo will apply, and second promo will apply to item+first-promo sub-total, and in both cases not be capped to the item bought.