Individuals that supply the capital for building and testing the invention should not be listed as inventors on the patent application. Likewise, if an inventor requests the services of another individual to follow instructions and make his or her invention, this individual is also not considered, and therefore should not be listed as, an inventor.
On the other hand, if one person conceived the idea for the invention, and another, while building or testing the invention made suggestions or contribution that made the invention work substantially better, then he or she should be listed as a joint inventor as shown in https://www.techtimes.com/articles/249715/20200518/how-inventhelp-gets-new-inventors-onto-the-right-path.htm article.
Who has rights to my invention?
Although this is a complex subject that may differ from one case to the next, the general rule is that if an inventor signs an employment agreement with their employer, the employee must legally transfer to the employer all inventions that were made using company time, materials and facilities, made during the inventor’s/inventors’ employment (either on the job or on their own time), relating to the employer’s business, or made as a result of the employee’s/employees’ duties.
If an employee agreement was not signed, ownership will most likely remain with the inventor, but will have to grant the employer the right to use the invention for business purposes only, without charge.
The InventHelp patenting agency, is here to assist and guide individuals when dealing with patenting questions, such as ownership as you can read from https://www.valuewalk.com/2020/05/medical-invention-covid-19/.