JUSTICE STEIGMANN delivered the opinion of the court:

In this 2004 marriage dissolution proceeding between petitioner, Dustin Miller, and respondent, Bethany Miller, the trial court limited the number of witnesses each party could call at the custody hearing. The court ultimately made Dustin the custodian of the parties' two children.

Bethany appeals, arguing only that the trial court erred by limiting the number of witnesses who could testify at the custody hearing. Because Bethany failed to make an adequate offer of proof regarding what testimony her additional witnesses would provide, we affirm.

I. BACKGROUND

Dustin and Bethany were married in July 2001. During their marriage, they had two children, Alexander (born July 12, 2001) and Madeline (born May 6, 2003). In September 2004, Dustin filed separate petitions seeking (1) to dissolve the marriage and (2) temporary custody of the parties' two children. In October 2004, Dustin and Bethany entered into an agreed order, under which the trial court granted Dustin temporary custody of the parties' two children.

In early December 2004, the trial court entered an order (1) setting the case for a February 9, 2005, hearing on custody and other issues and (2) providing that if either party wanted to call more than two witnesses at the hearing, that party would need to request a pretrial conference at least seven days prior thereto.

In late January 2005, Bethany's counsel, F. Donald Heck, Jr., filed a motion to withdraw as her counsel. On February 2, 2005, the trial court granted Heck's motion, and two other attorneys, Richard D. Frazier and Scott D. Larson, took over as Bethany's counsel. That same day, Larson filed a motion to continue the February 9, 2005, hearing. At a February 7, 2005, hearing on that motion, Larson argued that a continuance was necessary because he needed time to discuss the case with Bethany and conduct discovery. Dustin's counsel argued against the continuance, pointing out that (1) the court's December 2004 order indicated that the parties had represented that they would be ready for the February 9, 2005, hearing; (2) in late December 2004, Larson sent Heck a motion to substitute Larson as Bethany's counsel, which Heck signed and returned to Larson later that month; and (3) in mid-January 2005, Frazier filed an entry of appearance as Bethany's counsel. After considering counsel's arguments, the court denied the motion to continue.

At the start of the February 9, 2005, custody hearing, Frazier asked the trial court to reconsider its ruling on the motion to continue, so that the court could hold a pretrial conference in accordance with its December 2004 order and Bethany could request eight additional witnesses. Frazier stated, in pertinent part, as follows:

"Your Honor, this is a custody case. Obviously[,] it's a very serious matter. We would have liked to have called 10 witnesses for the hearing today, and probably the most important witness that we--which we could have called today as a witness, although we did not allow [sic] him because we believe the 2 other occurrence witnesses were probably more important, is [Bethany's] current psychologist, Dr. Brian Heatherton. Now, the reason that would be important is the court is going to hear some issues concerning [Bethany's] mental condition, which basically [is that] she's been diagnosed as bipolar 2, which is a less severe form of bipolar 1, but his testimony concerning her treatment and her ability to care for her children would be very important for the court to hear, I think.

We also would have other witnesses who would also be occurrence witness[es] because of, again, this court's reasonable pretrial order, but, again, it was not complied with, including a mentor and a priest of both individuals, who would give the court helpful information, Dr. Dennis Schafer, and other occurrences witnesses, such as [Bethany's] father; [Bethany's] sister, *** Sister Mary Ellen at QUANADA [(an organization that provides services for victims of domestic violence and sexual assault)], who would testify concerning some emotional and physical abuses that may have occurred during the marriage, and 2 other witnesses, Danny Reid and Monica Esela, who also could testify concerning what their observations were of the parties concerning the 2 children in this matter."

After considering counsel's argument, the trial court declined to reconsider its ruling, and the hearing proceeded. Dustin testified on his own behalf and called two witnesses, his mother and sister. Bethany testified on her own behalf and called two witnesses, her mother and a family friend. After considering the evidence, the court made Dustin the custodian of the parties' children.

This appeal followed.

II. ANALYSIS

A. Offers of Proof

When a party claims she has not been given the opportunity to prove her case because the trial court improperly barred certain evidence, she "must provide [the] reviewing court with an adequate offer of proof as to what the excluded evidence would have been." In re Estate of Romanowski, 329 Ill. App. 3d 769, 773, 771 N.E.2d 966, 970 (2002). An offer of proof serves two primary functions: (1) it discloses to the trial court and opposing counsel the nature of the offered evidence, thus enabling the court to take appropriate action, and (2) it provides the reviewing court with an adequate record to determine whether the trial court's action was erroneous. People v. Thompkins, 181 Ill. 2d 1, 10, 690 N.E.2d 984, 989 (1998).

The traditional way of making an offer of proof is the "formal" offer, in which counsel offers the proposed evidence or testimony by placing a witness on the stand, outside the jury's presence, and asking him questions to elicit with particularity what the witness would testify to if permitted to do so. People v. Wallace, 331 Ill. App. 3d 822, 831, 772 N.E.2d 785, 794 (2002); M. Graham, Cleary & Graham's Handbook of Illinois Evidence