What is the best entity to pack the intermediate in the offer->intermediate_link->coupon?

Question

PostgreSQL

Good afternoon.
There are 2 tables
offers (offer)
.id
.date_from
.date_to
.name
deals (coupons)
.id
.offer_id
.name
.price_from
.price_to
This was originally the final structure. But the customer made changes and a hierarchy appeared:
Offer_1
Entity_intermediate_link - 1 day
Coupon_1 person - own price
Coupon_2 people - own price
Entity_intermediate_link - 2 days
Coupon_1 person - own price
Coupon_2 people - own price
Moreover, Entity_intermediate_link - own pricemay be completely absent or, for example, there may be a combined version of the offer, where some coupons fall directly from it, and some from Essence_intermediate_link
Please advise - where is the best place to put this thing. I roughly believe that there are several solutions:
1. Make the offer hierarchical
2. Make the coupon hierarchical
3. Create a new table
Give good advice, fellow programmers.
According to 1-2 options, it is embarrassing that some fields in their case will be empty.
According to the 2nd option, it is confusing that it will be necessary to add the type (deal / category) field.
In the third, I don’t see any special advantages.
In addition to the question, if 1. or 2. - would it be correct to store the hierarchy in the adjacency list?