The collision on Saturday near Leyland, Lancashire resulted in the deaths of the Porsche driver and Faye Dawson.
Police said the driver of the Porsche, a 79-year-old man, joined at junction 28 via the southbound slip road.
Paying tribute, her family previously said Faye, of Wallasey, Merseyside, was "such a clever little girl who was very funny and had us all laughing all the time".
Three-year-old girl and man killed in crash.
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