Tracking shares of mutual during rebalancing

If the rebalancing was accomplished by the advisor by actually SELLING one security and BUYING another security, then those are exactly the actions you take in your Quicken file.  You mimic exactly what your advisor did.  If the "sale" transaction was for less than all of the security sold you should determine exactly what lots were sold by the advisor and select those same lots in your Quicken file.  If the "buy" was done in a series of separate purchases at different prices then you'd do likewise in your Quicken file.  (This assumes the transactions took place in an after-tax account and you want to track that account precisely in Quicken.)

If the rebalancing was done use tax-free exchanges of one fund for another fund, i.e., if the transactions would not create taxable gain or loss in an after-tax account, then you'd use either the "Corporate Acquisition (stock for stock)" or "Mutual Fund Conversion" action to mimic your advisor's transactions.  (The Mutual Fund Conversion action seems to have problems if you're using "average cost" for the shares, so make a backup - which you should do in any case - before entering your transactions.)