Hello @aclementerodrguez ,
I have arrived to the same conclusion : when I create a subscription with only basic plan then the id related to the product is similar to every offers unless there are differents ids per offers.
I think that to handle multiple offers of one subscription there is no others possibilities to create a whole new subscription and also to remind the player to cancel the previous subscription if the new one offers the same benefits, with only a different price and duration.
I have implemented 1 subscription on my recent game “Choco Math” ( Do you love Chocolate? ) with a classical offer of x € per month only and it simplify the process.
The multiple handling of subscription is I think not still available on Solar2d.