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SharePoint Online custom form add columns to an existing list

Hi All,


I am using a SharePoint Online customizable form to try making a bill of material app whereby a user can submit a bill of materials for a project.

The way I am trying to achieve this is that a user opens a form selects an existing project via a lookup, then selects a vendor and then the user can add an item from a hardware list (using cascading drops or something of the like).

The user selects the pieces of hardware they need, they are presented with an indicative cost and then submits the form. If the user needs to add another line, they click a button and another line appears.


I have multiple lists:



HardwareList (For each vendor)

BOM (Master list)


Where I am getting confused is that I want this data to be entered into the master list however each project will have a different number of items. Is it possible to make the form add additional columns to the master list when required or do you just have to prepopulate a set number of columns (i.e. Item 1/Item 20/etc) or am I just going about this the wrong way?


I have searched for days to try and find the answer but I'm not having any luck. Any help is greatly appreciated!

Not applicable


Prepopulating the list via sharepoint would be the easiest option. Or you could use Microsoft flows to create Sharepoint lists however this would mean everytime a user submits there form they would be calling a flow. (This isn't a bad thing, just depends on how many flows you have compared to the level of users using the application)

Community Support
Community Support

Hi @Obstruktion 


You want to save data in BOM list?

You can use patch function to achieve that.


More information:



Best Regards.


Not applicable

Hi @Obstruktion how are you progressing with this? Were the above replies helpful?



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