This paper examines the production of word-initial stops by two simultaneous trilingual sisters, aged 6;8 and 8;1, who receive regular input in Italian and English from multiple speakers, but in Spanish from only one person. The children's productions in each language were analyzed acoustically and compared to those of their main input providers. The results revealed consistent cross-linguistic differences by both children, including between Italian and Spanish stops, although these have identical properties in the speech of Italian- and Spanish-speaking adults. While the children's English stops were largely target-like, their Italian stops exhibited non-target-like realizations in the direction of English, suggesting interactions. Interestingly, their Spanish productions were largely unaffected by cross-linguistic interactions, with target-like voiceless stops, and voiced stops predominantly realized as spirants. These findings raise interesting questions about phonological development in multilingual settings and demonstrate that the number and type of input providers may crucially affect cross-linguistic interactions.