Whoa, so first thing you need to clarify is what bank accounts are coming into play, specifically, which bank accounts are you reconciling, because any entries you make (in Sage50, i.e. "the books") will need to match the bank statement for that particular bank account.

Additionally, if the company is incorporated, I don't think there is such a thing as "shareholder contributions" ... from my limited understanding, it's either a case of "owner's contributions" in the case of a sole proprietorship, or in the case of a corporation, "contributed capital" usually means a stock purchase by the shareholder.

If the owner is making a purchase for the company from his/her own personal bank account, then I'd be inclined to  suggest you do up an expense form for the items for which the owner needs to be reimbursed, and thus cut them a cheque for those funds.

Alternatively, you could enter the purchases to hit owner's/shareholder's account, that is, their "Loan from Shareholder" account in the Long-term Liabilities section of your chart of accounts. In this case there's no direct reimbursement to the shareholder as it becomes part of their 'value' in the company instead.

I agree with Kristine2012, with two clarifications:

1.  I suggest avoiding any use of 'contributed capital' unless you have something from an accountant or lawyer specifically telling you to use a contributed capital account.

2.  I tend to run all company-items-paid-by-shareholder and all personal-items-paid-by-company through the shareholder loan account.  I find it saves a lot of time, as I don't have to keep track of which specific items the shareholder has been reimbursed for.  If the shareholder puts money in or out fairly often, I will set the account up as a 'bank' so I can 'pay invoices' using it.  If the loan account has a credit balance, it means the shareholder's total contributions have been more than the total reimbursements/draws, and they can still take some money with no tax consequences.  If the loan account is in a debit balance, it means that the shareholder should talk to their accountant/tax planner about possible tax consequences.

An example of how simple the shareholder loan account can make my life as a bookkeeper is the situation where a shareholder pays a bunch of items on a personal credit card, and then pays the entire credit card bill using company funds because it was 'mostly used for the business this month'.  My procedure goes like this:

Step 1:  Personal credit card paid with company funds.  This is a shareholder loan draw.  (Dr shareholder loan, Cr bank).  At this stage, I really don't care what the card was 'mostly' used for.

Step 2:  When the shareholder gets around to giving me an itemized credit card statement, hopefully with receipts for all the company-related items, I record the expenses as Dr expenses, Cr shareholder loan account.  The end result is that the personal use of the credit card has been recorded as a draw against the loan account, and all of the expenses I've recorded are documented.