Hopefully, you have limited number of jobitem records to show in the grid. If this is the case then you could do following:
1. Create and fill the cursor containing both jobitem fields and partno field from another table.
2. Use this cursor as grid's recordsource.
3. Retrieve parts key on save point, when you save data from the cursor to jobitem table.

>I'm trying to get a GRID working for this scenario:
>
>Here are the relevant fields I will be asking about below:
>
>JobItem.iPartKey
>
>Parts.PartNo
>Part.ipkey
>
>I have a relation in place between JobItem.iPartKey->Parts.ipkey.
>
>As you can see, I have a JobItem table which stores a key (iPartKey) that points to they key of a Parts.ipkey. Now the user will not enter the key value (it is autoinc), rather, they will enter a part number which I need to lookup the corresponding "part key" for that part number in the Parts table and store the part key in JobItem.iPartKey.
>
>So I need to let them enter a part NUMBER in the column textbox, but I need to lookup that string in the Parts.PartNo, and get the Parts.ipkey, and strore that integer value in JobItem.iPartKey.
>
>In that column, I need to display Parts.PartNo, but the underlying value that makes it work is JobItem.iPartKey.
>
>I think I need to use the DynamicCurrentControl property to let the grid display the Parts.PartNo value, but I cannot get all the settings right to let me enter a value in the textbox, validate it (do the look up), set the JobItem.iPartKey, but display the Part.ParNo.
>
>
>Please help. What all do I need to support this structure.
>
>
>Here's the textbox.valid() code from my lookup textbox class that I have as one of the controls in the grid colum. After it validates the entered Part Number, I can then read the corresponding key value by referencing this.ipkey.
>
>

>Dimension laProperties(10)
>
>Local llValidated, lcLookup
>
>laProperties='' && Blank out the entire array (char type)
>laProperties[1]=0 && int type for iPartKey
>laProperties[4]=0.00 && Numeric type for price
>laProperties[7]={  /  /  } && Date type for date_added
>
>
> IF !Empty(this.value)
>
> *-- Determine exact size of PartNo fields---
> lcPartNo=Padr(Alltrim(this.Value),Fsize('part_no', 'Parts'))
>
> *-- 2008-09-02: Added support for AltPPartNo lookup
>  Select iPkey, part_no, altpartno, dwg_no, price, cust_num ,vendor, date_added, makebuy;
>   From parts;
>   Where part_no==lcPartNo;
>   Into Array laProperties
>
>   If _tally=0
>     MessageBox('Part No not found.',16,'Notice:')
>    Else
>     llValidated=.t.
>    endif
>
>  Endif 
>
>  this.ipkey=laProperties[1]
>  this.cPart_no=laProperties[2]
>  this.cAltPartNo=laProperties[3]
>  this.cDwg_no=laProperties[4]
>  this.nPrice=laProperties[5]
>  this.cCustno=laProperties[6]
>  this.cVendno=laProperties[7]
>  this.dDate_added=laProperties[8]
>  this.cMakeBuy=laProperties[9]
> 
>  this.found=Iif(llValidated or Empty(this.value), 1, 0)
>  this.refresh
>  return (this.found)
>
>