My daughter (over 26 yrs old) is currently enrolled in a plan through Obamacare. On March 1st, she can get insurance through a temporary job. The insurance will end in September. Can she stop the plan through Obamacare, take the insurance through the temporary job, then re-enroll in an Obamacare plan when the temporary insurance ends in September?
As long as someone has major medical coverage, they can switch to another major medical plan when that plan ends (unless it ends due to non-payment or fraud).
If the temporary health insurance is considered short term (thus not a major medical plan that counts as Minimum Essential Coverage), then instead she should use the fact that she is turning 26 to qualify for a Special Enrollment Period in the Health Insurance Marketplace.