The free will becomes a part of the primary cause by freely directing it to one of the various possible effects. It is not that it is free of the universal chain but rather it is one of the determining factors that results in a possible effect that the primary cause can cause and continues the universal chain on its way.
the will is not a primary cause
the will is always contingent
the will is caused
it sounds like you're suggesting "the will is free to choose between options" but those options are never equal
and even when the available options might appear to be roughly equal
choosing between roughly equal options is not properly described as "an intentional act of will"
it's just a roll-of-the-dice at that point
indistinguishable from random
and a random selection is not an intentional act of will
If you want, it is the thing that freely says "do this effect." That is why we hold people responsible for their actions. They directed a cause to a positive or negative effect. If the resultant effect was evil, they get punished. As in the case of willfull murder. If the resultant effect was not evil, as in the case of someone choosing a certain burger at the restuarant for the first time, we need not hold them accountable for any evil.
you keep using the word "freely" without indicating what exactly you believe it is "free" from
Similarly also, this choice of which effect is intentional. Meaning a person did it. If there is no intention, there is no immediate culpability to the effect. As in the case of motor accidents. Culpability is not determined by the fact that you crashed, it is determined by what you chose to do that caused the crash.
well, there is still "criminal negligence"
and "driving while intoxicated"
so, lack-of-intention is not exactly a moral "free-pass"