Direct and indirect pronouns together 1

IOP before DOP — the fixed order — When both a direct object pronoun and an indirect object pronoun appear together, the order is always IOP + DOP: me lo, te la, se los, nos lo. They go before a conjugated verb: Me lo dijo. Te la mandan. This order never reverses.

Le/les → se before lo/la/los/las — When the IOP is le/les and the DOP is any form of lo/la, the IOP changes to se: Le lo doy → Se lo doy. Les la mandaron → Se la mandaron. The form le lo simply does not exist. Always substitute se when these two pronouns meet.

Clarifying the ambiguous se — Since se replaced le/les and can mean to him/her/you/them, clarification is often added: Se lo expliqué a ellos. Se lo di a usted. The se pronoun stays — the phrase just removes ambiguity. This clarifying phrase is not optional if the meaning would otherwise be unclear.