I have discovered that I have inadequate support for a stairwell in my home. The support posts rests between floor joists, with no foundation pillar underneath. What is the best way to install a foundation pillar in an existing crawlspace?

I have discovered that I have inadequate support for a stairwell in my home. The support posts rests between floor joists, with no foundation pillar underneath. What is the best way to install a foundation pillar in an existing crawlspace?
First up, Is there room for crossblocks to support the subfloor between joists under both stairwell pillars? Secondly, is there any crawl headroom to dig footing holes for pier and posting to a short girder support of the subfloor blocking? You may not need the beam, but it would level out the load more evenly. You might beef up the stairs with a center stringer also.