Does the extension I already filed cover my dependent college student child if it turns out he will need to file a separate return? Should he file his own extension?

Our dependent student is listed on our prior returns.  Unlike prior years, this year they've received direct disbursements of grant $ refunds, some of which may be taxable but we haven't been able to figure that out yet.  Are they covered as a household member under the extension I already filed, or should we preemptively file a separate extension for them just in case we encounter complications with their filing status later on?