Can I be held liable if the company of which I am a co-owner is not doing well (can the liquidator show up at my doorstep)?

No, a liquidator can only hold the BV's board accountable.

In addition, participants will generally not acquire a "Substantial Interest" (5% or more). This means you are seen as a minority shareholder and are excluded from everything. In the event of bankruptcy (and thus when the liquidator intervenes), everyone, of course, loses their investment.