CRM suggestion for startup looking to manage relationships with partners and investors

We have used google sheets up to this point but google sheets does not enable parent child relationships among rows, and any kind of sorting we want to do with rows based on certain columns becomes complicated because child rows do not sort with the parent rows.. (in our particular case, the parent row is the company and the child rows are all the various contacts we have in that company and relevant info in other columns related to each column)

Does anyone have any recommendations for online spreadsheets or CRM's that can enable this?

Thanks in advance!