Can one parent request a children's aid society investigate the other parent's home before a parenting trial?

A parent can report a genuine safety concern about the other parent's home to a children's aid society at any time, including while a parenting trial is approaching, and the society will decide independently whether an investigation is warranted based on the information provided - a parent cannot simply direct the society to investigate as a litigation tactic, and the society isn't an arm of the family court process. If there's a real concern, report it honestly and completely, and let the society make its own determination about what steps, if any, are warranted.

Courts are alert to the possibility of reports being made or timed strategically to influence an upcoming trial, and a pattern of reports that closely track the litigation timeline, especially if they turn out to be unfounded, can itself become an issue the court considers when assessing a parent's credibility and conduct. If you have a legitimate concern close to trial, document why now, be straightforward with the society about the basis for the concern, and let your lawyer know you've made the report so it can be addressed properly rather than appearing to have been sprung on the other side or the court unexpectedly.