So far as I am aware, all the SSPX schools in the USA and Canada (and possibly worldwide?) use the dialogue Mass.
As to whether children are “forced” to say it, I am guessing the instance discussed in the other thread was a rather isolated occurrence, since most SSPXers no longer object to the dialogue Mass (ie., one must object and resist before anyone could attempt to enforce making the responses).
I am of the opinion that there are several reasons those in the English-speaking countries have swallowed this modernist novelty:
1) It was permitted before Vatican II, therefore it must be traditional;
2) Archbishop Lefebvre allowed it, therefore it must be traditional;
3) the slow but steady and incremental changes in the postures of the faithful over the last 15+ years have trended in this direction at the sung Masses, such that the delta between congregational responses at the sung mass, and the audible responses of the faithful at the low Mass, is not objectionable: the principle is the same.
4) The faithful are ignorant of the liturgical reform, and consequently do not understand that some of the principles cited in favor of the dialogue Mass (eg., using the Mass as a training ground, or as a catechism, or to further active participation, etc. are modernist innovations which were not concerns -and were unheard of except in Protestant circles- just 110 years ago;
5) That all these ideas were condemned and suppressed until the reign of Benedict XV, and that these subversive liturgical innovators met in secret in places like Assisi, Maria Lach, etc, and held conferences sponsored by liberal modernist bishops, who took us their projects and gave them safety, promoting their poisonous efforts.
6) That Rome initially objected, but the liberal bishops multiplying, and Benedict XV and Pius XI not having the same metal as St. Pius X, Rome gave in to keep the appearance of being in control.
THAT IT IS AN OUTRAGE TO ATTRIBUTE THE IMPETUS TO ST PIUS X, WHO HIJACKED HIS LEGITIMATE REFORMS, AND WHO ABSOLUTELY NEVER ENCOURAGES “ACTIVE PARTICIPATION” (THE WORD FOR WHICH DOES NOT APPEAR IN THE OFFICIAL VERSION OF HIS ENCYCLICAL, AND WHO NEVER ENCOURAGED CONGREGATIONAL SINGING)
Anyone who supports the dialogue Mass, by that very fact, has become a useful idiot for the liturgical revolutionaries.