Perhaps Richard, you should start by realizing that gunmakers often used more than one marking punzon, with slight variations; and that drawings pulled by book authors are not necessarily so exact as suc irons used.
If you compare the drawings in Lavin and Soler, you will notice that they are different; in Lavin, Luis's lion has some something in his paws and in Soler's he has nothing.
But if you look at actual irons that were used in those smiths guns, as illustrated and described in Catálogo de Arcabuceria Madrileña, you will see and read that both father and son marks have a fleur-de-lis in the right paw, although
some time Luis doesn't use it. The more notable difference is that Juan used a radiant star in the top left corner, although
his father also eventually used it.
... If i am not talking nonsense ... Fernando, tocayo ?