Mapping and spraying play a crucial role in precision agriculture. In some technologies, companies employ an offline approach to plan paths for a swarm of UAVs. However, in real-world scenarios, unforeseen challenges often arise during missions, necessitating adaptive path adjustments. Currently, human intervention remains common to address these issues as they occur. In this regard, greater autonomy will likely be essential. To address these dynamic and uncertain situations, this paper introduces a novel online planner designed to enable UAVs to make slight adjustments to their pre-planned paths in real time until issues are resolved. This proposed approach facilitates autonomous online path planning that seamlessly integrates both pre-planned and dynamically adjusted routes. Primary planning is carried out offline, with the online planner activated to handle unexpected challenges as they arise. Depending on the circumstances, UAVs can collaborate to resolve issues while adhering to specified constraints to achieve their objectives.