If you aren't sure there are too many debts, you can follow the procedure to make an inventory of the inheritance. It is more costly than just accepting the inheritance. Just accepting the inheritance can be done without any formailty, but has the disadvantage that you will be liable for all the debts, even when you need to pay more than what you recieved from the inheritance..
Following the procedure with an inventory has the advantage that you will never have to pay more for debts of the inheritance than what you recieved from the inheritance.
The inventory must be made by a notary. In practice the declaration of accepting the inheritance under the procedure of making an inventory can be made, and then the inventory will be made.
In the Cicil code it's requested to make the inventory first and then do the declaration, but in practice this isn't always respected. The idea of the civil code is that first you make an inventory. This should be done within 3 months. Then after the inventory is finised, you should made the declaration within 40 days. But in practice it's considered that even years after the deceasure, it's still possibe to follow the procedure with inventory, as long as you didn't accepyt the inheritance.