ASA Softball Rule

[Boomer3]

Okay guys, I've umpired college and high school baseball for years. Now playing ASA Senior Softball and need help on a rule. Can't find it in rule book, but it may be in a case book. In baseball there is a thing called the "initial play" rule as involves obstruction and interference. Basically, a fielder has the initial chance to field a ball without being interfered with by a runner. However, should he boot the ball and have to go after it, he is no longer protected from an interference call and may be called for obstruction of the runner should his chasing down his booted ball take him into the path of the runner advancing to next base. Well, I can't find anything that mentions this rule in the ASA Softball Rules Book. Need some help on this one as it seems to be a regular occurrence with us concrete handed geezers in the over 50 league.